{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.wm-xct-011","code":"wm-xct-011-identifier-scheme","url":"https://ver.cy/models/wm-xct-011-identifier-scheme/","name":"Identifier Scheme","alternateNames":["N8"],"kind":"world-model","status":"published","version":"0.3.0-research.1","language":"en","classifiers":{"family":"World Models","category":"Cross-cutting context","entryKind":"mixin","plane":"","domain":["XCT.IDS"],"industry":["Cross-industry"],"navPath":"NAV.XCT.IDS","tags":["identifier","scheme","xct.ids"],"facets":{}},"whatItIs":"In scope is the scheme as referent: how a scheme is constituted and registered, what strings it admits, how those strings are compared, who is mandated to allocate them and under what policy, how an identifier is bound to a referent and moves through states, whether and how it resolves, what persistence is promised, how it maps to other schemes, and what quality, privacy and legal constraints attach. Out of scope is the referent itself, the proof that a claimant is the entity a label denotes, and every storage or interface projection.","purpose":"Describe a governed naming system as a thing in the world - its constitution, syntax, authority, allocation, lifecycle, resolution, cross-scheme mapping and assurance - so that every other model can carry identifiers by mixing in one scheme-aware structure instead of re-inventing naming rules locally.","scope":{"in":["Scheme constitution: registry entry, namespace expression, referent class, scheme version and registration status","Lexical form: grammar, character repertoire, length, case rules, internal prefix structure, check character systems","Equivalence: canonical form, scheme-specific normalization, permitted and forbidden comparison transformations","Registration authority, mandate instrument, oversight body and accreditation of issuers","Sub-namespace delegation, prefix exclusivity, change controller and revocation of delegation","Allocation policy (private use, experimental, first come first served, expert review, specification required, hierarchical)","Assignment records binding an identifier to a referent, with assigner, evidence and effective period","Identifier state vocabulary and permitted transitions including deprecation, retirement, annulment and transfer","Reuse, reassignment, quarantine, supersession, split and merge rules","Namespace capacity, consumption and exhaustion planning","Resolution services, protocols, coverage and the separation of identification from dereference","Persistence commitments, tombstone behaviour and custody transfer","Cross-scheme mapping assertions with relation type, evidence and quality","Carriage of scheme identity alongside an identifier value in consuming models","Collision, squatting, alias and drift detection","Conformance evidence, defect rates and audit","Privacy classification of identifier values and disclosure risk","Legal mandate, licensing of registry and crosswalk data, and succession planning"],"out":["The referent itself - the person, organization, product, document, dataset or concept that an identifier denotes belongs to the model of that thing","Identity proofing, authenticator binding, authentication and federation - an identifier is a label, not a credential","Authorization and access control decisions taken on the basis of an identifier","Cryptographic key management, verification methods and signature suites used by self-certifying identifier methods","Organization master data for registration authorities, issuers and resolver operators beyond their mandate role","Semantic definition of concepts in a controlled vocabulary; only the notation and its uniqueness are in scope here","Transport, DNS operations, network routing and hosting of resolver infrastructure","Record linkage and probabilistic entity resolution techniques used to reconcile records that lack a shared identifier","Storage and interface projections: JSON, YAML, Markdown, HTML, Git, MCP and MongoDB are renderings, not semantics"],"boundaries":[{"neighbor":"Digital identity and authentication model","distinction":"NIST SP 800-63-4 separates resolution of a subject, validation of evidence, creation of a subscriber account and binding of authenticators; this model covers only the label and its governance, never the proof that a claimant is the entity the label denotes. An identifier must never be treated as an authenticator."},{"neighbor":"Controlled vocabulary / concept scheme model","distinction":"A SKOS concept scheme governs meaning and is deliberately open-boundaried; an identifier scheme governs denotation and uniqueness of a string over referents. skos:notation is the single overlap point: the notation string is in scope here, the concept it labels is not. Code lists such as ISO 3166 sit ambiguously across this line and are recorded as an unresolved boundary."},{"neighbor":"Organization model","distinction":"Registration authorities, oversight committees, local operating units and resolver operators are organizations; only the mandate, accreditation status and change-controller role are modelled here, by reference. GLEIF, the Regulatory Oversight Committee and accredited issuers illustrate the three distinct roles."},{"neighbor":"Service and endpoint model","distinction":"RFC 3986 section 1.2.2 states that a URI provides identification only and that access is neither guaranteed nor implied; resolver endpoints, protocols and service levels are described here as declared properties of the scheme, while the operational service belongs to a service model."},{"neighbor":"URI scheme registry / protocol registry model","distinction":"BCP 35 governs the registration of URI scheme names as protocol elements with permanent, provisional or historical status; that registry is itself an identifier scheme instance under this model, not a separate meta-layer. Registration of a scheme name is distinguished from allocation of identifiers under it."},{"neighbor":"Privacy and data protection model","distinction":"GDPR Article 4(1) makes an identification number or online identifier a route to identifiability, and Article 87 leaves national identification numbers to Member State law; this model records the classification and disclosure risk of identifier values, while lawful basis, impact assessment and data subject rights belong to the privacy model."},{"neighbor":"Agreement and licensing model","distinction":"Registration contracts, resolution service terms and bulk crosswalk licences are agreements; this model records only their existence, the obligations they impose on registrants and the continuity commitments they encode."}]},"distinguishingFeatures":["An identifier scheme defines how identifiers are formed, assigned, compared and resolved, not the referents themselves.","It differs from a controlled vocabulary, whose codes carry meaning, and from authentication.","Reuse and persistence rules are recorded per scheme, never assumed.","Comparison uses the scheme's own rules, not a generic normalizer."],"structure":{"bundles":[{"id":"scheme-constitution","name":"Scheme Constitution and Lexical Form","description":"What the scheme is, which strings it admits, when two strings denote the same thing, and how much meaning the string is allowed to carry.","layers":[{"id":"scheme-identity-and-scope","name":"Scheme Identity and Scope","description":"The scheme as a first-class referent: its registry key, namespace expression, class of referents, version and registration status.","findings":[{"id":"scheme-identity-record","name":"Scheme identity, namespace expression and referent class","description":"An identifier scheme is itself a referent that must be identifiable, scoped and statused before any identifier under it can be interpreted. Its identity comes from an entry in a governing registry (an IANA URN namespace identifier, a URI scheme name, an ISO 6523 code designator, a DID method name), and its scope is the declared class of referents it may name. The namespace expression is the token a consuming model carries next to the value so that the value can be interpreted at all.","questions":[{"text":"Which authoritative registry entry establishes this scheme, and under what key?","id":"q-scheme-registry-key","kind":"identity"},{"text":"What class of referents may be named under this scheme, and what is explicitly excluded?","id":"q-scheme-referent-class","kind":"classification"},{"text":"What namespace expression must accompany a value of this scheme when it is carried inside another model?","id":"q-scheme-namespace-expression","kind":"interoperability"},{"text":"Is the scheme versioned, and does a version change alter the meaning of identifiers already assigned?","id":"q-scheme-version-effect","kind":"temporal"},{"text":"What is the scheme's registration status and when did that status last change?","id":"q-scheme-status","kind":"state"}]}]},{"id":"lexical-form-and-validation","name":"Lexical Form and Validation","description":"The grammar, repertoire and self-checking machinery that decide whether a candidate string is a well-formed identifier of this scheme.","findings":[{"id":"identifier-syntax-grammar","name":"Identifier grammar, repertoire and internal structure","description":"The decidable definition of a well-formed identifier: a formal grammar, the permitted character repertoire and encoding, length bounds, case treatment, and which substrings are structurally significant. RFC 8141 requires a syntax statement in every namespace registration and constrains namespace identifiers to a bounded alphanumeric pattern; RFC 3986 requires a scheme's own syntax to remain within the generic grammar; DOI names divide at a forward slash into an issuer prefix and a registrant-chosen suffix; the LEI is a fixed twenty-character code whose leading characters denote the issuing unit.","questions":[{"text":"What machine-checkable expression defines a well-formed identifier of this scheme?","id":"q-syntax-expression","kind":"constraint"},{"text":"Which characters and encodings are permitted, and how is case treated?","id":"q-syntax-repertoire","kind":"constraint"},{"text":"Which substrings of an identifier are structurally significant, and what do they delimit?","id":"q-syntax-structure","kind":"composition"},{"text":"What minimum and maximum lengths apply, and are they enforced at assignment or only at validation?","id":"q-syntax-length","kind":"constraint"},{"text":"How are historical values that fail the current grammar handled?","id":"q-syntax-legacy","kind":"exception"}]},{"id":"check-character-and-validation","name":"Check character systems and what validity proves","description":"Many schemes carry a self-checking element - LEI check digits, an ARK check character computed over a defined check zone, or the version and variant bits of a UUID - that detects transcription error. This finding separates three distinct claims that are routinely confused: the string is well-formed, the string passes its internal check, and the string has actually been assigned to a referent by the authority. Only the third is evidence of existence.","questions":[{"text":"What check character algorithm applies, and over which part of the string is it computed?","id":"q-check-algorithm","kind":"measurement"},{"text":"What does a passing check prove, and what does it not prove?","id":"q-check-meaning","kind":"evidence"},{"text":"Which authority must be consulted to confirm that a well-formed identifier has actually been assigned?","id":"q-validity-authority","kind":"authority"},{"text":"If the scheme has no check element, what compensating control detects transcription error?","id":"q-check-absent","kind":"quality"}]}]},{"id":"equivalence-and-canonical-form","name":"Equivalence and Canonical Form","description":"When two strings denote the same referent, which transformations preserve identity, and which comparison level a consumer is entitled to apply.","findings":[{"id":"equivalence-and-normalization-rules","name":"Scheme-specific equivalence and normalization rules","description":"Comparison is not a generic operation. RFC 3986 sets out a ladder from simple string comparison through syntax-based and scheme-based normalization to protocol-based normalization, with each rung raising both true-positive and false-positive rates. RFC 8141 requires case normalization of the scheme token and namespace identifier while forbidding percent-decoding and requiring optional components to be ignored. XML namespace names are compared as identical character sequences with no escaping done or undone. ARK normalization removes the resolver host, lowercases the authority number and treats hyphens as insignificant. A single global normalizer applied across schemes will merge distinct referents.","questions":[{"text":"What is the canonical form of an identifier of this scheme, and how is it derived?","id":"q-canonical-form","kind":"definition"},{"text":"Which transformations preserve identity for this scheme and which must never be applied?","id":"q-equivalence-transforms","kind":"constraint"},{"text":"Which comparison level is a consumer entitled to rely on without contacting the authority?","id":"q-comparison-level","kind":"constraint"},{"text":"Which form is stored and indexed, and is the form as received also retained?","id":"q-storage-form","kind":"quality"},{"text":"Does the scheme permit more than one identifier for the same referent, and how are aliases declared?","id":"q-alias-policy","kind":"relationship"}]}]},{"id":"semantic-transparency-and-opacity","name":"Semantic Transparency and Opacity","description":"How much the identifier string is permitted to say about its referent, and what that disclosure costs.","findings":[{"id":"opacity-and-embedded-semantics","name":"Opacity policy and embedded semantics","description":"W3C web architecture advises that agents should not infer properties of a referent from its identifier, and ARK strongly encourages semantic opacity so that names survive changes in the world. Yet delegated-prefix schemes deliberately embed the issuing authority in the string, which is exactly what makes decentralised allocation work. This finding records what the scheme permits to be inferred, what must never be inferred, and what the structure discloses to an observer who was never meant to know it.","questions":[{"text":"What may an agent legitimately infer from the structure of an identifier of this scheme?","id":"q-inference-permitted","kind":"interoperability"},{"text":"What must an agent never infer from an identifier value, even when the pattern appears to support it?","id":"q-inference-forbidden","kind":"constraint"},{"text":"What does the identifier disclose to an observer who holds only the string?","id":"q-semantic-leakage","kind":"access"},{"text":"If an embedded attribute of the referent changes, does the identifier change?","id":"q-semantic-drift","kind":"lifecycle"}]}]}]},{"id":"authority-and-registration","name":"Authority, Delegation and Registration Policy","description":"Who is mandated to run the scheme, how that mandate is sub-delegated, under what policy identifiers and sub-namespaces are handed out, and what the registration record must contain.","layers":[{"id":"registration-authority-and-mandate","name":"Registration Authority and Mandate","description":"The party that holds the scheme mandate, the instrument granting it, the body that oversees it, and the evidence of its fitness to endure.","findings":[{"id":"authority-mandate-and-accreditation","name":"Mandate, oversight and issuer accreditation","description":"A scheme's credibility rests on a named party holding an identifiable mandate. RFC 8141 asks a formal-namespace registrant to demonstrate organizational stability, competence in assignment and a commitment not to reassign. ITU-T X.660 establishes published procedures for object identifier registration authorities. The LEI system separates three roles that are often collapsed: a regulatory oversight committee, a foundation acting as administrator, and accredited local operating units that actually issue. The DOI system likewise separates a single registration authority from a network of registration agencies.","questions":[{"text":"Who holds the mandate for this scheme, and under what instrument was it granted?","id":"q-mandate-holder","kind":"authority"},{"text":"Which body oversees the mandate holder, and what powers does it hold?","id":"q-oversight-body","kind":"authority"},{"text":"How are issuing bodies accredited, and how is accreditation withdrawn?","id":"q-issuer-accreditation","kind":"process"},{"text":"What evidence supports the mandate holder's ability to sustain the scheme over its intended horizon?","id":"q-stability-evidence","kind":"evidence"},{"text":"What happens to assignments and resolution if the mandate holder ceases to operate?","id":"q-authority-failure","kind":"exception"}]}]},{"id":"delegation-and-sub-namespaces","name":"Delegation and Sub-Namespaces","description":"How allocation authority is subdivided, whether delegation is exclusive, who controls change to a given entry, and how delegation ends.","findings":[{"id":"delegation-chain-and-change-control","name":"Delegation chain, exclusivity and change controller","description":"Hierarchical allocation lets delegated administrators control portions of a namespace while a higher authority manages the levels above, and RFC 8126 names it as a policy in its own right. The Handle System builds naming authorities as a dotted tree in which global uniqueness follows from a globally unique authority combined with a locally unique name. DOI achieves decentralised allocation the same way. Delegation raises questions the parent scheme must answer: is a delegated prefix exclusive against longer strings sharing its leading characters, who may change an entry once delegated, and what happens to identifiers already issued when a delegation is revoked.","questions":[{"text":"How is allocation authority subdivided, and what is the shape of the delegation tree?","id":"q-delegation-mechanism","kind":"composition"},{"text":"Is a delegated namespace portion exclusive, and does it foreclose overlapping allocations?","id":"q-delegation-exclusivity","kind":"constraint"},{"text":"Who is the change controller for a given registry entry or delegated namespace?","id":"q-change-controller","kind":"ownership"},{"text":"On what grounds can a delegation be revoked, and what becomes of identifiers already issued under it?","id":"q-delegation-revocation","kind":"lifecycle"},{"text":"May a delegate sub-delegate further, and is the parent bound by the delegate's policy?","id":"q-delegation-recursion","kind":"authority"}]}]},{"id":"allocation-policy-and-registry-record","name":"Allocation Policy and Registry Record","description":"The rule by which new registrations and allocations are granted, and the fields the resulting record must carry.","findings":[{"id":"allocation-policy","name":"Allocation policy and reserved ranges","description":"RFC 8126 supplies the working vocabulary: Private Use and Experimental Use where nothing is recorded centrally, Hierarchical Allocation where administrators control portions, First Come First Served with no substantive review, Expert Review, Specification Required which additionally demands a permanent and readily available public specification, and the progressively stricter document-based policies. It also distinguishes Unassigned from Reserved and introduces Known Unregistered Use as a warning marker. A scheme that cannot name its policy cannot tell a consumer how much review any given identifier has had.","questions":[{"text":"Which allocation policy governs new registrations under this scheme?","id":"q-allocation-policy-value","kind":"authority"},{"text":"If review is required, who performs it and against what published criteria?","id":"q-designated-experts","kind":"process"},{"text":"Which value ranges are reserved, private-use, experimental or otherwise withheld from allocation?","id":"q-reserved-ranges","kind":"classification"},{"text":"Can the allocation policy itself be changed, and by what procedure?","id":"q-policy-change","kind":"process"},{"text":"How does the scheme record values known to be in use without a registration?","id":"q-unregistered-use","kind":"exception"}]},{"id":"scheme-registration-template-record","name":"Registration template content and entry deprecation","description":"RFC 8141 makes a namespace registration carry purpose, syntax including equivalence rules, assignment mechanism, security and privacy analysis, interoperability conflicts, and a resolution statement, with a pointer to a stable specification. BCP 35 adds status, applications and protocols, contact and change controller. RFC 8126 further allows a registry to be closed or marked obsolete and individual entries to be deprecated with annotations preserved for history. These filed statements are the primary machine-readable evidence about a scheme and are frequently the only evidence available to a consuming agent.","questions":[{"text":"Which registration template fields were filed, and which mandatory fields are missing or empty?","id":"q-template-completeness","kind":"evidence"},{"text":"Where is the permanent and readily available public specification for this scheme?","id":"q-permanent-specification","kind":"provenance"},{"text":"What security and privacy analysis was filed with the registration?","id":"q-filed-security-privacy","kind":"evidence"},{"text":"How is a registry entry deprecated or obsoleted, and what annotation survives?","id":"q-entry-deprecation","kind":"lifecycle"}]}]}]},{"id":"assignment-and-lifecycle","name":"Assignment, State and Continuity","description":"The act of binding an identifier to a referent, the states that binding passes through, whether a retired identifier may ever be used again, and whether the namespace will hold out.","layers":[{"id":"assignment-act-and-binding","name":"Assignment Act and Binding","description":"The record of who bound which identifier to which referent, when, on what evidence, and with what obligatory metadata.","findings":[{"id":"identifier-assignment-record","name":"Assignment record: referent binding, assigner, evidence and period","description":"The assignment is the atomic fact this model exists to support. The FHIR Identifier datatype gives the minimal shape a consumer needs: a system establishing the namespace, a value unique within it, an optional coded type, a use marker that modifies interpretation, a validity period and an assigner. DataCite shows that a registration agency may impose mandatory descriptive metadata as a condition of assignment. RFC 8141 requires the assignment mechanism and its uniqueness method to be specified. Event time and record time must be kept apart: when the binding took effect is not when the register learned of it.","questions":[{"text":"Which referent is bound by this assignment, and how is that referent itself identified?","id":"q-assignment-referent","kind":"identity"},{"text":"Who performed the assignment, under which delegated authority?","id":"q-assignment-assigner","kind":"authority"},{"text":"When did the assignment take effect, and when was it recorded?","id":"q-assignment-time","kind":"temporal"},{"text":"What evidence supports that the referent is what the registrant claims it to be?","id":"q-assignment-evidence","kind":"evidence"},{"text":"What metadata or conduct obligations does the registrant accept as a condition of assignment?","id":"q-assignment-obligations","kind":"requirement"},{"text":"What is the intended use of this identifier relative to any others held by the same referent?","id":"q-assignment-use","kind":"classification"}]},{"id":"granularity-qualifiers-and-notations","name":"Granularity, qualifiers and notations","description":"ISO 26324 and ISO 24619 require explicit granularity. ARK qualifiers identify parts and variants. SKOS notations are lexical codes unique within a concept scheme and are not a substitute for URIs. Fragments and f-components identify constituents without changing the assigned name.","questions":[{"text":"At what granularity is the identifier defined, and may finer parts be addressed by qualifiers or fragments rather than new assignments?","id":"granularity-qualifiers-and-notations-q01","kind":"composition"},{"text":"If a notation or code is used, is it unique only within a concept scheme, and what URI or URN is the preferred computational identifier?","id":"granularity-qualifiers-and-notations-q02","kind":"interoperability"},{"text":"Do content-negotiated, language, format or version variants share the assigned name or require distinct identifiers?","id":"granularity-qualifiers-and-notations-q03","kind":"classification"}]}]},{"id":"identifier-state-model","name":"Identifier State Model","description":"The state vocabulary an identifier moves through and the transitions the scheme permits.","findings":[{"id":"identifier-lifecycle-states","name":"State vocabulary, transitions and consumer duties","description":"Identifiers are not simply present or absent. The LEI system publishes an explicit registration status vocabulary covering issued, lapsed, merged, retired, annulled, duplicate and transfer states, tied to a renewal obligation. The IANA language subtag registry carries deprecation as a dated field with an optional preferred-value pointing at a successor, while never removing the record. RFC 8126 separates unassigned from reserved. DID methods must define a deactivate operation. A consuming agent needs to know not only the current state but what it is now obliged to do.","questions":[{"text":"What is the complete state vocabulary for an identifier under this scheme?","id":"q-state-vocabulary","kind":"state"},{"text":"Which state transitions are permitted, and who may trigger each one?","id":"q-state-transitions","kind":"lifecycle"},{"text":"What must a consumer do when an identifier it holds becomes deprecated or retired?","id":"q-consumer-duty-on-deprecation","kind":"requirement"},{"text":"Does the scheme impose a renewal or revalidation duty, and what happens if it lapses?","id":"q-renewal-obligation","kind":"requirement"},{"text":"How does a consumer determine the current state of an identifier, and how fresh is that answer?","id":"q-state-observation","kind":"access"}]}]},{"id":"reuse-succession-and-continuity","name":"Reuse, Succession and Referent Change","description":"Whether a retired identifier may be bound again, and how splits, merges and transfers of the referent are expressed.","findings":[{"id":"reuse-and-reassignment-policy","name":"Reuse policy, quarantine and supersession","description":"Non-reuse is a policy choice, not a law of naming, and this is where naive models fail. RFC 8141 asks formal-namespace registrants to demonstrate a commitment not to reassign, and BCP 47 guarantees that subtags are never removed or reassigned. GS1 by contrast operated timed reuse until an all-sector non-reallocation rule took effect after December 2018, and it still permits reuse twelve months after catalogue deletion for items that were never produced, while withdrawn-and-reintroduced items keep their original identifier. Supersession, splits and merges need explicit relation vocabulary of the kind DataCite provides.","questions":[{"text":"Does this scheme permit a retired identifier to be bound to a different referent?","id":"q-reuse-permitted","kind":"constraint"},{"text":"If reuse is permitted, what quarantine period and preconditions apply?","id":"q-reuse-quarantine","kind":"constraint"},{"text":"When custody of the referent transfers, does the identifier travel with it?","id":"q-referent-transfer","kind":"ownership"},{"text":"How are splits and merges of the referent expressed in identifier terms?","id":"q-split-merge","kind":"relationship"},{"text":"How can a consumer detect that an identifier it holds now denotes a different referent?","id":"q-reuse-detection","kind":"quality"}]},{"id":"split-merge-and-alias-continuity","name":"Split, merge and aliasing","description":"Public identities and bibliographic identifiers are sometimes merged or split. SKOS exactMatch is transitive and maps concepts across schemes without asserting owl:sameAs. A resource may carry several URNs for similar or different purposes, which is aliasing rather than merge.","questions":[{"text":"If two identifiers were merged, which value survives, which are aliases, and is the merge reversible?","id":"split-merge-and-alias-continuity-q01","kind":"relationship"},{"text":"If one identifier was split, which new identifiers were minted for which new referents, and what is the parent identifier?","id":"split-merge-and-alias-continuity-q02","kind":"event"},{"text":"Are multiple identifiers for one referent true aliases, purpose-specific identifiers, or embeddings of another scheme?","id":"split-merge-and-alias-continuity-q03","kind":"classification"}]}]},{"id":"namespace-capacity","name":"Namespace Capacity and Exhaustion","description":"How many identifiers the scheme can still issue, how fast it is consuming them, and what happens when it runs out.","findings":[{"id":"capacity-and-exhaustion-planning","name":"Capacity, consumption rate and extension strategy","description":"Namespace exhaustion is a foreseeable failure with long lead times and is routinely omitted from scheme documentation. RFC 9562 makes the point in the probabilistic case: implementers must weigh the consequences of collision and choose between local and global uniqueness guarantees. ARK addresses the combinatorial case directly by recommending digit-heavy names with sparing use of a restricted alphabet to raise namespace density. Hierarchical schemes shift the problem to the delegation tree, where a parent can extend capacity by widening or deepening arcs.","questions":[{"text":"What is the theoretical capacity of this namespace under its current grammar?","id":"q-capacity-total","kind":"measurement"},{"text":"What is the observed allocation rate, and what is the projected exhaustion date?","id":"q-consumption-rate","kind":"measurement"},{"text":"How can capacity be extended without invalidating existing identifiers?","id":"q-extension-strategy","kind":"decision"},{"text":"For probabilistically generated identifiers, what collision probability is accepted and on what basis?","id":"q-collision-tolerance","kind":"constraint"}]}]}]},{"id":"resolution-and-persistence","name":"Resolution, Dereference and Persistence","description":"Whether the scheme resolves at all, through which services, what a resolution returns, and what is actually being promised about the future.","layers":[{"id":"resolution-service","name":"Resolution Service","description":"The services that dereference identifiers of this scheme, their protocols, coverage and operators.","findings":[{"id":"resolver-endpoint-and-protocol","name":"Resolver endpoints, protocols and coverage","description":"The Handle System illustrates the general architecture: a global registry maps a naming authority to the local service responsible for it, clients cache that mapping, and resolution requests proceed without authentication unless confidential values are involved. RFC 8141 reserves a resolution parameter component but forbids its use before semantics are standardised, and requires a resolution statement in the registration. DID methods must each define a resolve operation. Coverage matters as much as the endpoint: a resolver that covers only part of a namespace produces silent failures indistinguishable from non-existence.","questions":[{"text":"Is resolution intended for this scheme at all, and what did the registration state?","id":"q-resolution-intended","kind":"definition"},{"text":"Which services resolve identifiers of this scheme, over which protocols?","id":"q-resolver-endpoints","kind":"process"},{"text":"What portion of the namespace does each resolver actually cover?","id":"q-resolver-coverage","kind":"quality"},{"text":"Are resolution parameters or service requests supported, and with what standardised semantics?","id":"q-resolution-parameters","kind":"interoperability"},{"text":"What service level, caching guidance and rate limits govern resolution at volume?","id":"q-resolution-terms","kind":"constraint"}]},{"id":"identification-versus-dereference","name":"Identification distinguished from dereference","description":"RFC 3986 states that a URI provides identification only and that access to the resource is neither guaranteed nor implied, and it discourages the strict name-versus-locator partition on which many identifier arguments rest. XML namespace names are explicitly not intended for retrieval. Yet FAIR expects data to be retrievable by identifier over a standardised protocol, and users routinely treat a failed resolution as evidence that the referent does not exist. This finding fixes the interpretation a consuming agent must apply so that resolution failure is not mistaken for non-existence, nor successful resolution for authenticity of the referent.","questions":[{"text":"Does holding a well-formed identifier of this scheme guarantee any access to the referent?","id":"q-access-guarantee","kind":"constraint"},{"text":"What may a consumer conclude when resolution fails?","id":"q-failed-resolution-meaning","kind":"exception"},{"text":"Is the scheme's own namespace expression intended to be dereferenceable?","id":"q-namespace-dereference","kind":"interoperability"},{"text":"Does successful resolution establish that the returned resource is the intended referent?","id":"q-resolution-authenticity","kind":"evidence"}]},{"id":"scheme-specific-resolution-parameters","name":"Resolution parameters and DID URL options","description":"RFC 8141 r-components are reserved for passing parameters to resolution services and must not affect assigned-name equivalence. DID parameters service, relativeRef, versionId, versionTime and hl distinguish which resource is identified versus how resolution is performed.","questions":[{"text":"Does this scheme define r-component or equivalent resolver parameters, or are they still undefined and therefore not to be used?","id":"scheme-specific-resolution-parameters-q01","kind":"constraint"},{"text":"Which DID URL parameters are supported to select service, relative resource, version or hash integrity?","id":"scheme-specific-resolution-parameters-q02","kind":"interoperability"},{"text":"Which inputs must be part of the identifier URL and which must be resolver options that are not part of identity?","id":"scheme-specific-resolution-parameters-q03","kind":"decision"}]}]},{"id":"persistence-commitment","name":"Persistence Commitment","description":"Who promises what, for how long, and what survives when the referent does not.","findings":[{"id":"persistence-policy-and-commitment-statement","name":"Persistence commitment, horizon and tombstone behaviour","description":"ARK is unusually explicit that persistence is purely a matter of service and that only a current provider can say what commitment it intends; its policy service returns declarations addressing object availability, identifier validity, content invariance and change history. FAIR asks separately that metadata remain accessible even when the data are not. W3C web architecture asks owners to provide representations consistently and predictably. Together these give four separable promises that are routinely bundled into the single unfalsifiable word persistent.","questions":[{"text":"Who makes the persistence commitment for a given identifier, and are they the current provider?","id":"q-commitment-parties","kind":"ownership"},{"text":"Which of identifier validity, object availability, content invariance and change history are actually promised?","id":"q-commitment-content","kind":"requirement"},{"text":"Over what horizon does the commitment run, and what backs it?","id":"q-commitment-horizon","kind":"temporal"},{"text":"What is returned once the referent is withdrawn, and is its metadata retained?","id":"q-tombstone","kind":"exception"},{"text":"How is the commitment transferred if custody of the referent or the resolver changes?","id":"q-custody-transfer","kind":"process"}]}]},{"id":"resolution-response-and-metadata","name":"Resolution Response and Metadata","description":"What a resolution returns, how metadata is requested, and how the outcome is recorded.","findings":[{"id":"resolution-outcome-record","name":"Resolution outcome, returned values and audit trail","description":"A handle carries multiple typed and indexed values, each with its own administrative controls, so resolution returns a value set rather than a single location. ARK reserves an inflection that returns descriptive metadata together with the commitment statement. DID resolution returns a document plus resolution metadata. For an operating agent the outcome must be recorded with the identifier as supplied, the identifier as canonicalized, the resolver consulted, the observation time and the outcome class, because the same identifier resolved at two times is two facts.","questions":[{"text":"What does a successful resolution return, and is it a single value or a typed set?","id":"q-resolution-return","kind":"definition"},{"text":"How does a client request descriptive metadata or a policy statement rather than the referent?","id":"q-metadata-request","kind":"process"},{"text":"What outcome classes must a client distinguish, and how are they signalled?","id":"q-outcome-classes","kind":"exception"},{"text":"What must be recorded about a resolution so that the result can be reproduced or disputed later?","id":"q-resolution-audit","kind":"provenance"}]},{"id":"access-controlled-and-failing-resolution","name":"Access-controlled and failing resolution","description":"RFC 8141 contemplates authorised retrieval of representations while others receive only metadata, as in a national legal-deposit collection. Resolution may also be undefined for namespaces that identify protocol features rather than retrievable resources. Failure modes and caching must not equate non-retrieval with non-identity.","questions":[{"text":"Who may obtain a representation versus metadata versus a mere existence check, and under which exception process?","id":"access-controlled-and-failing-resolution-q01","kind":"access"},{"text":"If the scheme is not intended as a locator, what does software that obtains the identifier do instead of retrieval?","id":"access-controlled-and-failing-resolution-q02","kind":"exception"},{"text":"How are not-found, gone, unauthorised and resolver-unavailable distinguished in logs without treating them as identifier invalidity?","id":"access-controlled-and-failing-resolution-q03","kind":"exception"}]}]}]},{"id":"interoperability-and-mapping","name":"Interoperability, Carriage and Conflict","description":"How identifiers of this scheme relate to identifiers of other schemes, how they travel inside other models, and how collisions and drift are detected.","layers":[{"id":"crosswalks-and-mappings","name":"Crosswalks and Mapping Assertions","description":"Declared correspondences between identifiers or schemes, with relation type, evidence and quality.","findings":[{"id":"cross-scheme-mapping-assertion","name":"Mapping assertion: relation type, evidence, quality and chaining","description":"A crosswalk is an assertion by a party, not a fact of the world. SKOS distinguishes exact, close, broad, narrow and related matches, declares exactMatch transitive and symmetric while deliberately withholding transitivity from closeMatch so that errors do not compound when mappings are chained across schemes, and makes exactMatch disjoint from broadMatch and relatedMatch. DataCite supplies a complementary vocabulary for identity and version relations between registered resources. Every assertion needs an asserter, evidence, a quality judgement and a retirement path.","questions":[{"text":"What relation type does this mapping assert, and is it symmetric or transitive?","id":"q-mapping-relation-type","kind":"relationship"},{"text":"Who asserted this mapping, on what evidence, and when?","id":"q-mapping-asserter","kind":"provenance"},{"text":"What is the quality of this mapping and how was it measured?","id":"q-mapping-quality","kind":"measurement"},{"text":"May this mapping be chained with others to infer a further correspondence?","id":"q-mapping-chaining","kind":"constraint"},{"text":"How is a mapping withdrawn when one side is deprecated or reassigned?","id":"q-mapping-retirement","kind":"lifecycle"},{"text":"What cardinality does the mapping have, and how are one-to-many correspondences represented?","id":"q-mapping-cardinality","kind":"composition"}]}]},{"id":"carriage-and-embedding","name":"Carriage and Embedding in Consuming Models","description":"How an identifier travels inside another model so that it stays interpretable, comparable and attributable.","findings":[{"id":"identifier-carriage-profile","name":"Carriage profile: system plus value, use, assigner and period","description":"This is the mixin surface. FHIR's Identifier shows the minimum that must travel with a value for it to remain interpretable: a system establishing the namespace, the value unique within it, a coded type, a use marker that modifies meaning, a validity period and an assigner. XML Namespaces warns that a prefix functions only as a local placeholder and that applications should use the namespace name, not the prefix, whenever a name's scope extends beyond its document. ISO 6523 code designators show the same job done with a numeric scheme code instead of a URI. A consuming model that stores a bare string has thrown away the interpretation.","questions":[{"text":"What must accompany an identifier value for a consumer to interpret it without external context?","id":"q-carriage-shape","kind":"interoperability"},{"text":"Are abbreviations or prefixes permitted in carriage, and is their scope local only?","id":"q-carriage-prefix","kind":"constraint"},{"text":"When a referent holds several identifiers, how is the preferred one designated?","id":"q-carriage-multiplicity","kind":"classification"},{"text":"How is the period during which an identifier was valid for the referent recorded?","id":"q-carriage-period","kind":"temporal"},{"text":"How is the assigning body recorded alongside the value?","id":"q-carriage-attribution","kind":"provenance"}]},{"id":"embedding-and-encapsulation","name":"Embedding and encapsulation","description":"RFC 8141 allows NSS to encapsulate hierarchical names from non-URN systems. ISO 26324 describes integrating another scheme character string through DOI syntax or system metadata. FHIR says if the value is a full URI then system SHALL be urn:ietf:rfc:3986. Embedding is not the same as mapping.","questions":[{"text":"Does this identifier embed another scheme native string, and what canonicalisation is applied before embedding?","id":"embedding-and-encapsulation-q01","kind":"composition"},{"text":"Can the native identifier be recovered losslessly from the encapsulating form, and which form is canonical for matching?","id":"embedding-and-encapsulation-q02","kind":"interoperability"},{"text":"Does the encapsulating scheme claim to replace the native scheme, contrary to ISO 26324 non-replacement rule?","id":"embedding-and-encapsulation-q03","kind":"constraint"}]},{"id":"computational-identifier-tuple","name":"Computational identifier tuple","description":"FHIR Identifier shows the operational pattern every consuming model needs: system namespace URI, value unique in that system, optional type, use, period and assigner. Comparison requires knowing the system. Values are case-sensitive unless the system says otherwise.","questions":[{"text":"What absolute namespace URI is the system, and what value is unique within it?","id":"computational-identifier-tuple-q01","kind":"identity"},{"text":"Is a coded identifier type recorded for when the system is unknown, without treating type as a substitute for system?","id":"computational-identifier-tuple-q02","kind":"classification"},{"text":"What normalisation is allowed before matching, and is case-insensitive comparison actually safe for this system?","id":"computational-identifier-tuple-q03","kind":"validation"}]}]},{"id":"collision-drift-and-conflict","name":"Collision, Drift and Conflict","description":"Detecting duplicate denotation, unauthorised use and silent divergence from the governing scheme.","findings":[{"id":"collision-and-drift-detection","name":"Collision, squatting, aliasing and upstream drift","description":"W3C web architecture names two failure modes directly: collision, where distinct resources share an identifier, and aliasing, where one resource acquires arbitrarily many. BCP 35 warns against squatting and requires a new scheme to show utility beyond what is already registered. RFC 8126 provides a marker for values known to be in use without registration. BCP 47 shows the hardest case: an upstream source standard withdraws or reassigns a code, and the registry must absorb the change through deprecation and preferred-value mappings rather than by removing the record. Carrying the scheme version alongside every stored value is what makes such drift detectable at all.","questions":[{"text":"What counts as a collision under this scheme, and how is one detected?","id":"q-collision-definition","kind":"quality"},{"text":"When two identifiers are found to denote the same referent, which survives and how is the other marked?","id":"q-duplicate-resolution","kind":"decision"},{"text":"How is use of unregistered or squatted values discovered and handled?","id":"q-unauthorised-use","kind":"exception"},{"text":"When an upstream source standard changes a code, how does the scheme absorb the change?","id":"q-upstream-drift","kind":"process"},{"text":"What signal lets a consumer detect that stored values no longer match the scheme in force?","id":"q-drift-detection-signal","kind":"quality"}]}]}]},{"id":"assurance-risk-and-compliance","name":"Assurance, Privacy and Legal Continuity","description":"Whether the scheme's claims can be checked, what risk its values carry, and what legal footing keeps it running.","layers":[{"id":"quality-and-conformance","name":"Quality and Conformance Evidence","description":"What is claimed, what evidence supports it, and how defects are measured and remedied.","findings":[{"id":"conformance-and-quality-evidence","name":"Conformance claims, defect measurement and audit","description":"External standards are alignments until evidence is produced. A conformance claim must name the standard, the edition and the specific clause, and point at the test or audit that supports it. GLEIF's data quality programme shows that a registry's assertions about its own contents are measurable and reportable rather than declaratory. Mandatory metadata properties give a concrete completeness measure. Where no evidence exists, the honest record is an alignment claim, not conformance.","questions":[{"text":"Which standard, edition and clause does this scheme claim conformance to, and what evidence supports the claim?","id":"q-conformance-claim","kind":"evidence"},{"text":"What defect rate is observed in the assignment register, and how is it measured?","id":"q-defect-rate","kind":"measurement"},{"text":"Who audits the scheme's operation, how often, and what are the published findings?","id":"q-audit-regime","kind":"authority"},{"text":"What is the remediation path when a defect or non-conformance is found?","id":"q-remediation","kind":"process"},{"text":"Which external standards are aligned with but not conformed to, and where do they diverge?","id":"q-alignment-not-conformance","kind":"interoperability"}]}]},{"id":"privacy-and-disclosure-risk","name":"Privacy and Disclosure Risk","description":"Whether identifier values are personal data, what they leak, and what they must never be used for.","findings":[{"id":"identifier-privacy-classification","name":"Personal-data classification, leakage and misuse as a credential","description":"GDPR Article 4(1) makes an identification number or online identifier a route to identifiability, Recital 26 keeps re-identifiable pseudonymised data within scope, Recital 30 names device and cookie identifiers explicitly, and Article 87 leaves national identification numbers to Member State law. RFC 8141 requires a filed analysis of comparison issues, information leakage and privacy. Time-based generated identifiers can disclose creation time and generator state. NIST separates a label from a credential: an identifier is never proof of anything, and treating it as an authenticator is a design fault, not a policy preference.","questions":[{"text":"Are values of this scheme personal data, directly or through re-identification?","id":"q-personal-data-status","kind":"classification"},{"text":"What does a value disclose about its referent or its creation to a party holding only the string?","id":"q-value-leakage","kind":"access"},{"text":"Can the namespace be enumerated or harvested, and what controls limit that?","id":"q-enumeration-risk","kind":"access"},{"text":"Is the value ever accepted as evidence of authorisation or identity, and how is that prevented?","id":"q-credential-misuse","kind":"constraint"},{"text":"How is an erasure or restriction request reconciled with a persistence commitment?","id":"q-erasure-vs-persistence","kind":"exception"},{"text":"Does any national or sectoral restriction limit processing of this identifier?","id":"q-national-number-restriction","kind":"authority"}]}]},{"id":"legal-basis-and-continuity","name":"Legal Basis, Licensing and Continuity","description":"The instrument the scheme runs on, the terms on which its data may be used, and what happens if the operator stops.","findings":[{"id":"mandate-licensing-and-succession","name":"Legal instrument, data licensing and succession planning","description":"A scheme's data has terms even when it is free: the LEI system is presented as a public good available free to all users, which is itself a licensing position with consequences for downstream reuse. Registration agencies impose obligations on registrants as a condition of assignment. RFC 8126 requires change control to be settled per registry and, where entries come from many sources, per entry. ARK's observation that only a current provider can state its intended commitment makes succession the central continuity question: if the operator stops, the commitment stops unless someone has already agreed to inherit it.","questions":[{"text":"Under what legal instrument does the scheme operate, and in which jurisdictions is it effective?","id":"q-legal-instrument","kind":"authority"},{"text":"On what terms may the registry, assignment register and crosswalk data be used and redistributed?","id":"q-data-licence","kind":"access"},{"text":"What ongoing obligations bind a registrant, and what are the fees?","id":"q-registrant-obligations","kind":"requirement"},{"text":"Who inherits the scheme, its register and its resolution duty if the operator winds down?","id":"q-succession-plan","kind":"process"},{"text":"Who holds change control over the scheme record and over individual entries?","id":"q-change-control-legal","kind":"ownership"}]}]}]}]},"agentConduct":{"may":["Validate a candidate identifier against its scheme syntax and check digits.","Canonicalize identifiers using scheme rules.","Resolve identifiers through the scheme's resolver.","Detect collisions and aliasing across schemes."],"mustNot":["Treat an identifier as proof of identity or authorization.","Reuse an identifier where the scheme forbids it.","Apply one normalizer across schemes.","Claim persistence without a named provider commitment.","Bulk export assignment registers without audit."],"requiresHuman":["Registering a new scheme or transferring registration authority.","Changing reuse rules.","Asserting cross-scheme mappings used for legal identity."]},"ethics":{"considerations":["Personal identifiers enable tracking and linking across contexts.","Identifier errors can wrongly link people or deny them services."],"affectedParties":["People and organizations identified","Scheme users","Registration authorities"]},"owners":{"steward":"The adopting Dimension must name a scheme registrar role accountable for scheme records, delegation entries and allocation policy, distinct from the registrants who own facts about their own referents.","roles":[{"name":"Scheme registrar","responsibilities":["Own scheme records, syntax and equivalence rule sets, allocation policy and delegation entries","Approve and publish amendments with effective timestamps and grandfathering statements","Maintain the register of adopted schemes and their versions for the Dimension","Publish the collision and drift report and assign remediation owners"]},{"name":"Allocation authority or accredited issuer","responsibilities":["Assign identifiers within a delegated namespace portion and record assigner, evidence, effective and record times","Enforce uniqueness, quarantine and reuse eligibility before binding","Maintain mandatory registration metadata conditions on registrants","Report allocation rates for capacity forecasting"]},{"name":"Registrant","responsibilities":["Own the facts about the referent an identifier denotes and keep required metadata current","Meet renewal or revalidation obligations before lapse","Notify the issuer of referent transfer, withdrawal, split or merge","Accept the recorded conditions of assignment"]},{"name":"Resolution operator","responsibilities":["Operate resolver endpoints within a declared coverage and service level","Publish and honour the persistence commitment for the portions it currently controls, including tombstone behaviour","Record resolution outcomes with observation times for audit","Reissue or transfer commitments when custody changes"]},{"name":"Mapping steward","responsibilities":["Assert and maintain cross-scheme mappings with relation type, evidence, quality and chaining permission","Withdraw mappings when either side is deprecated or reassigned","Measure and publish mapping quality and known systematic errors","Prevent uncontrolled transitive inference across chained mappings"]},{"name":"Assurance and privacy reviewer","responsibilities":["Classify each adopted scheme for personal-data status, leakage and enumerability per jurisdiction","Verify that conformance claims cite standard, edition, clause and evidence, and downgrade unsupported claims to alignments","Audit bulk exports of assignment and crosswalk data","Confirm that no system accepts an identifier value as an authenticator"]}],"masterSystems":[]},"relations":[{"target":"Any Vercy model carrying identifier-valued data elements","type":"composes","note":"Supply the carriage shape - namespace token, value, type, use marker, validity period and assigner - so that a consuming model stores an interpretable identifier instead of a bare string, and so that scheme drift is detectable at the point of use."},{"target":"Organization model","type":"references","note":"Registration authorities, oversight bodies, accredited issuers, registrants and resolver operators are organizations; this model holds only their mandate and role, never their master data."},{"target":"Controlled vocabulary and concept scheme model","type":"aligned","note":"Align the notation carried by a concept with this model's identifier value, while leaving concept meaning, scheme membership and semantic relations to the vocabulary model; the alignment point is notation as a typed literal."},{"target":"Service and endpoint model","type":"references","note":"Resolver endpoints, protocols and service levels are described here as declared scheme properties and referenced to the service model for their operational reality, monitoring and incident history."},{"target":"Digital identity and authentication model","type":"references","note":"Record the hard boundary that an identifier is a label and never a credential; proofing, authenticator binding and authentication belong entirely to the identity model."},{"target":"Privacy and data protection model","type":"references","note":"Carry the privacy classification of identifier values into lawful-basis, impact-assessment and data-subject-rights processing without duplicating those processes here."},{"target":"Agreement and licensing model","type":"references","note":"Registration contracts, resolution service terms and bulk crosswalk licences are agreements; this model records their existence, obligations and continuity effects only."},{"target":"RFC 8141 Uniform Resource Names","type":"aligned","note":"Align namespace registration, equivalence procedure and the mandatory registration template fields; alignment only, since conformance for any given scheme requires an actual IANA registration as evidence."},{"target":"RFC 3986 URI Generic Syntax","type":"aligned","note":"Align the comparison ladder and the principle that identification does not imply access, which together fix how far a consumer may normalize and what a resolution failure means."},{"target":"RFC 8126 IANA registration policies","type":"aligned","note":"Adopt the allocation policy vocabulary and the reserved-value status terms so that any scheme can state how much review its identifiers have had."},{"target":"ITU-T X.660 object identifier registration authority procedures","type":"aligned","note":"Align the registration authority and hierarchical arc delegation pattern; cited only to the extent the published abstract supports, since the full text was not retrievable during research."},{"target":"HL7 FHIR Identifier datatype","type":"aligned","note":"Adopt the system-plus-value carriage pattern with use, type, period and assigner as the reference shape for the mixin surface."},{"target":"SKOS mapping relations","type":"aligned","note":"Adopt the mapping relation vocabulary including the deliberate non-transitivity of close matches, which constrains crosswalk chaining."},{"target":"Event and audit log model","type":"composes","note":"Identifier state transitions and resolution attempts are events; compose the shared event structure so that effective time and observation time are always recorded separately."},{"target":"Referent model of the named thing","type":"references","note":"Every assignment points at a referent whose description, class and lifecycle belong to that referent's own model; this model asserts only the binding and its evidence."},{"target":"Digital identity and authentication model","type":"neighbor","note":"NIST SP 800-63-4 separates resolution of a subject, validation of evidence, creation of a subscriber account and binding of authenticators; this model covers only the label and its governance, never the proof that a claimant is the entity the label denotes. An identifier must never be treated as an authenticator."},{"target":"Controlled vocabulary / concept scheme model","type":"neighbor","note":"A SKOS concept scheme governs meaning and is deliberately open-boundaried; an identifier scheme governs denotation and uniqueness of a string over referents. skos:notation is the single overlap point: the notation string is in scope here, the concept it labels is not. Code lists such as ISO 3166 sit ambiguously across this line and are recorded as an unresolved boundary."},{"target":"Organization model","type":"neighbor","note":"Registration authorities, oversight committees, local operating units and resolver operators are organizations; only the mandate, accreditation status and change-controller role are modelled here, by reference. GLEIF, the Regulatory Oversight Committee and accredited issuers illustrate the three distinct roles."},{"target":"Service and endpoint model","type":"neighbor","note":"RFC 3986 section 1.2.2 states that a URI provides identification only and that access is neither guaranteed nor implied; resolver endpoints, protocols and service levels are described here as declared properties of the scheme, while the operational service belongs to a service model."},{"target":"URI scheme registry / protocol registry model","type":"neighbor","note":"BCP 35 governs the registration of URI scheme names as protocol elements with permanent, provisional or historical status; that registry is itself an identifier scheme instance under this model, not a separate meta-layer. Registration of a scheme name is distinguished from allocation of identifiers under it."},{"target":"Privacy and data protection model","type":"neighbor","note":"GDPR Article 4(1) makes an identification number or online identifier a route to identifiability, and Article 87 leaves national identification numbers to Member State law; this model records the classification and disclosure risk of identifier values, while lawful basis, impact assessment and data subject rights belong to the privacy model."},{"target":"Agreement and licensing model","type":"neighbor","note":"Registration contracts, resolution service terms and bulk crosswalk licences are agreements; this model records only their existence, the obligations they impose on registrants and the continuity commitments they encode."}],"interaction":{"identity":{"applicability":"required","items":["The identifier issued by the authoritative master system for the artifact's subject - for a scheme record, the key issued by its governing registry; for an assignment, the assigned identifier itself.","A governed global identifier or IRI where no master-system key exists - the scheme's registered namespace URI, or a registered persistent identifier for a published report or dossier.","A UUID or ULID assigned by the adopting Dimension, explicitly recorded as locally scoped and carrying no external authority.","A date, a title, a file path or a storage location is never an identifier and must not be used as one, even provisionally."]},"properties":{"applicability":"not-applicable","items":[]},"recognition":{"applicability":"optional","items":["Recognised by syntax, prefix, check digit, and scheme name.","Confused with a code meaning a concept, a secret token, a URL and a similar-looking identifier from another scheme."]},"capabilities":{"applicability":"required","items":["Register an identifier scheme: Create or amend the record that constitutes a scheme in a governing registry, capturing purpose, syntax, equivalence rules, assignment mechanism, security and privacy analysis, interoperability conflicts and resolution intent.","Validate a candidate identifier: Decide whether a candidate string is well formed under the scheme's grammar, repertoire and length rules and whether it passes any check element, reporting the three validity levels separately.","Canonicalize an identifier value: Apply the scheme's own ordered normalization procedure to produce the canonical form used for storage, indexing and comparison, retaining the as-received form.","Delegate a sub-namespace: Grant allocation authority over a portion of the namespace to another party, recording exclusivity, change control, sub-delegation rights and effective period.","Assign an identifier to a referent: Bind a well-formed identifier to a referent, recording assigner, effective time, record time, evidence, use marker and any obligatory registration metadata.","Transition identifier state: Move an identifier to a new state in the scheme's state vocabulary, recording trigger, actor, successor where applicable, effective time and record time.","Evaluate reuse eligibility: Determine whether a retired identifier may be bound to a different referent under the scheme's reuse rule, its quarantine period and its stated exceptions, including rules that changed on a given date.","Resolve an identifier: Query a resolver for the values associated with an identifier, recording the resolver consulted, the outcome class and the observation time, and interpreting failure against the scheme's declared failure semantics.","Publish a persistence commitment: Issue a declaration by the current provider stating what is promised per dimension - identifier validity, object availability, content invariance, change history - over what horizon and with what exclusions.","Assert a cross-scheme mapping: Record a typed correspondence between an identifier or scheme and its counterpart in another scheme, with asserter, evidence, quality, cardinality and chaining permission.","Detect collision, aliasing and drift: Scan a population of stored identifiers for duplicate denotation, uncontrolled aliasing, known unregistered use and divergence from the scheme version currently in force.","Classify identifier privacy risk: Assess whether values of a scheme are personal data in a given jurisdiction, what they leak, whether the namespace is enumerable, and confirm the prohibition on treating the value as an authenticator.","Project a scheme registry view: Produce a projection over scheme records, delegations, allocation policies and resolver descriptors that omits individual assignments, for consumers who need to interpret identifiers without access to the register.","Transfer registration authority: Reassign change control or RA mandate when the original registrant is unreachable or an IESG or ISO decision requires it."]},"hazards":{"applicability":"required","items":["Collisions mixing records.","Enumeration of predictable identifiers exposing data.","Broken resolution after a provider change."]},"interfaces":{"applicability":"required","items":["ISO/IEC 15459 unique identification.","ISO 26324 Digital Object Identifier system.","ISO 7064 check character systems.","W3C Decentralized Identifiers (DIDs) v1.0."]},"context":{"applicability":"required","items":["The personal-data framing follows Regulation (EU) 2016/679, which applies to the EU and EEA. Article 87 expressly leaves national identification numbers to Member State law, so identifier-specific restrictions vary within the EU itself. Other regimes - United States sectoral rules including health identifiers, Brazil, India, China and others - impose different and sometimes incompatible constraints that were not researched.","The ISO 6523 code designator list is represented through a Peppol BIS Billing rendering, which reflects European cross-border electronic invoicing practice and may omit or reorder entries relative to the register of record.","The LEI governance model reflects a G20-backed supranational arrangement; national organization identifier schemes cited in the same code list operate under wholly different mandates, funding and public-access terms.","Retrieval itself was regionally constrained: several standards bodies returned 403 to automated access from the research environment, which biases the evidence base toward IETF, W3C and openly published first-party sources and away from ISO, IEC and ITU normative text.","Language and script assumptions are not neutral: the retrieved sources overwhelmingly constrain identifiers to ASCII or a restricted graphic repertoire, and internationalised identifier handling was not researched beyond the DOI statement about Unicode graphic characters.","IANA and ISO registries are treated as globally authoritative for the scheme classes they govern; national bibliographic or eID schemes may add regional RAs not listed here.","ARK NAAN registry hosting at CDL with mirrors at NLM and BnF is the current operational assumption, not a metaphysical lock-in.","GS1 check-digit rules as published by GS1 AISBL are used; national GS1 member organisations may add allocation policy.","English official names are stored as names; other language designations belong in a naming-convention sibling aligned with ISO/IEC 11179-5."]}},"sources":[{"title":"RFC 8141: Uniform Resource Names (URNs)","url":"https://www.rfc-editor.org/rfc/rfc8141.html","note":"Internet Engineering Task Force"},{"title":"RFC 3986: Uniform Resource Identifier (URI): Generic Syntax","url":"https://www.rfc-editor.org/rfc/rfc3986.html","note":"Internet Engineering Task Force"},{"title":"RFC 8126: Guidelines for Writing an IANA Considerations Section in RFCs","url":"https://www.rfc-editor.org/rfc/rfc8126.html","note":"Internet Engineering Task Force"},{"title":"RFC 7595: Guidelines and Registration Procedures for URI Schemes","url":"https://www.rfc-editor.org/rfc/rfc7595.html","note":"Internet Engineering Task Force"},{"title":"RFC 5646: Tags for Identifying Languages","url":"https://www.rfc-editor.org/rfc/rfc5646.html","note":"Internet Engineering Task Force"},{"title":"RFC 9562: Universally Unique IDentifiers (UUIDs)","url":"https://www.rfc-editor.org/rfc/rfc9562.html","note":"Internet Engineering Task Force"},{"title":"RFC 3650: Handle System Overview","url":"https://www.rfc-editor.org/rfc/rfc3650.html","note":"Internet Engineering Task Force / Corporation for National Research Initiatives"},{"title":"Uniform Resource Names (URN) Namespaces registry","url":"https://www.iana.org/assignments/urn-namespaces/urn-namespaces.xhtml","note":"Internet Assigned Numbers Authority"},{"title":"Architecture of the World Wide Web, Volume One","url":"https://www.w3.org/TR/webarch/","note":"World Wide Web Consortium"},{"title":"Namespaces in XML 1.0 (Third Edition)","url":"https://www.w3.org/TR/xml-names/","note":"World Wide Web Consortium"},{"title":"SKOS Simple Knowledge Organization System Reference","url":"https://www.w3.org/TR/skos-reference/","note":"World Wide Web Consortium"},{"title":"Decentralized Identifiers (DIDs) v1.1","url":"https://www.w3.org/TR/did-1.1/","note":"World Wide Web Consortium"},{"title":"FHIR Data Types: Identifier","url":"https://www.hl7.org/fhir/datatypes.html","note":"Health Level Seven International"},{"title":"Introducing the Legal Entity Identifier (LEI)","url":"https://www.gleif.org/en/about-lei/introducing-the-legal-entity-identifier-lei","note":"Global Legal Entity Identifier Foundation"},{"title":"DataCite Metadata Schema 4.6","url":"https://datacite-metadata-schema.readthedocs.io/en/4.6/","note":"DataCite e.V."},{"title":"FAIR Principles","url":"https://www.go-fair.org/fair-principles/","note":"GO FAIR International Support and Coordination Office"},{"title":"NIST Special Publication 800-63-4: Digital Identity Guidelines","url":"https://pages.nist.gov/800-63-4/sp800-63.html","note":"National Institute of Standards and Technology"},{"title":"Regulation (EU) 2016/679 (General Data Protection Regulation)","url":"https://eur-lex.europa.eu/eli/reg/2016/679/oj/eng","note":"European Parliament and Council of the European Union"},{"title":"The ARK Identifier Scheme (draft-kunze-ark)","url":"https://datatracker.ietf.org/doc/draft-kunze-ark/","note":"IETF Datatracker / ARK Alliance"},{"title":"ITU-T Recommendation X.660 | ISO/IEC 9834-1: Procedures for the operation of object identifier registration authorities","url":"https://www.itu.int/rec/T-REC-X.660/en","note":"International Telecommunication Union - Telecommunication Standardization Sector"},{"title":"DOI Handbook","url":"https://www.doi.org/the-identifier/resources/handbook/","note":"DOI Foundation (International DOI Foundation)"},{"title":"Can a GTIN be reused? (GS1 Global Office support knowledge base)","url":"https://support.gs1.org/support/solutions/articles/43000734390-can-a-gtin-be-reused-","note":"GS1 AISBL"},{"title":"ISO 6523 ICD list (Peppol BIS Billing 3.0 code list)","url":"https://docs.peppol.eu/poacc/billing/3.0/codelist/ICD/","note":"OpenPeppol AISBL"},{"title":"Uniform Resource Identifier (URI) Schemes","url":"https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml","note":"Internet Assigned Numbers Authority (IANA)"},{"title":"Decentralized Identifiers (DIDs) v1.0","url":"https://www.w3.org/TR/did-core/","note":"World Wide Web Consortium (W3C)"},{"title":"ISO 26324:2025 Information and documentation — Digital object identifier system","url":"https://www.iso.org/standard/88862.html","note":"International Organization for Standardization (ISO)"},{"title":"ISO/IEC 11179-1:2023 Information technology — Metadata registries (MDR) — Part 1: Framework","url":"https://www.iso.org/standard/78914.html","note":"ISO/IEC JTC 1/SC 32"},{"title":"ISO/IEC 6523-1:2023 Information technology — Structure for the identification of organizations and organization parts — Part 1: Identification of organization identification schemes","url":"https://webstore.iec.ch/en/publication/87933","note":"ISO/IEC JTC 1/SC 32"},{"title":"ISO 24619:2011 Language resource management — Persistent identification and sustainable access (PISA)","url":"https://www.iso.org/standard/37333.html","note":"International Organization for Standardization (ISO)"},{"title":"HL7 FHIR R5 Datatype Identifier","url":"https://hl7.org/fhir/datatypes-definitions.html#Identifier","note":"Health Level Seven International (HL7)"},{"title":"DOI Handbook","url":"https://www.doi.org/doi-handbook/html/index.html","note":"DOI Foundation"},{"title":"ARK NAANs and systems","url":"https://arks.org/about/ark-naans-and-systems/","note":"ARK Alliance / California Digital Library"},{"title":"GS1 check digit calculator and identification-key integrity","url":"https://www.gs1.org/services/check-digit-calculator","note":"GS1"}],"openQuestions":["E.164 numbering, number portability, reuse cooling-off and jurisdictional mandates.","Content-addressed identifiers such as multihash and CID, ledger addresses and quantum-resistant identifier suites.","Direct clause-level verification of paywalled ISO/IEC 11179, 7064, 6523, 9834, ISO 26324 and ISO 17442 texts.","Machine-readable scheme-description languages and automated publication tooling.","Registry dispute resolution, monopoly-registry economics and antitrust constraints.","ISO/IEC 11179-5 and 11179-6 on naming and registration principles, ISO/IEC 7064 on check character systems, ISO/IEC 6523 itself, ISO 26324, ISO 17442 and ISO 15511 could not be read directly; the ISO catalogue and browsing platform returned 403 throughout. Their content is reflected only through accessible first-party or downstream sources, and no clause-level claim is made about any of them.","The full text of ITU-T X.660 was not retrievable; object identifier arc allocation, unambiguous name rules and the international registration authority's procedures are asserted only at the level the published abstract supports.","The GS1 General Specifications full text exceeded the retrieval limit; the check digit calculation and company prefix exclusivity rule are known only through GS1 summary pages, and the non-reuse rule through a first-party support article citing section 4.2.5.","The ISO/IEC 6523 registration authority site was unreachable over HTTPS with an expired certificate; the ICD list is represented through a Peppol rendering, which is a downstream operational view rather than the register of record.","Whole identifier families were not researched: E.164 telephone numbering, postal and addressing codes, content-addressed identifiers such as multihash and CID, blockchain address schemes, biometric and behavioural identifiers, radio callsigns and spectrum registrations, and vehicle or aircraft registration schemes.","Machine-readable scheme description languages and the tooling that consumes them were not surveyed, so the model does not state how a scheme's syntax and equivalence rules should be published for automated use.","Economic and antitrust aspects of monopoly registries, and the dispute resolution procedures that mature registries operate, are represented only as questions without grounded answer structures.","ITU-T E.164 telephone numbering, number portability and reuse cooling-off were not fetched as primary text and are flagged as a likely reuse-policy omission.","ITU-T X.660 / ISO/IEC 9834 OID arc administration is only indirectly supported via urn:oid and FHIR oid, not as a full RA model.","W3C CURIE and prefix.cc community prefix governance lack a primary fetch in this run.","NISO, DataCite kernel, ORCID and ISNI merge procedures are discovered via IANA NID entries but not specified here as first-party operating manuals.","DID v1.1 Candidate Recommendation Snapshot of 5 March 2026 is emerging and not the alignment target.","Handle DO-IRP 2022 is cited from the DOI Handbook rather than fetched as a DONA primary.","Jurisdiction-specific civil identifiers (national ID, tax ID) are out of content scope; scheme-level privacy rules still apply if such a scheme is registered.","Quantum-resistant identifier cryptography and ledger-specific DID method suites are not specified."],"resources":{"spec":"/models/wm-xct-011-identifier-scheme/spec.yaml","agents":"/models/wm-xct-011-identifier-scheme/AGENTS.md","source":"https://github.com/ver-cy/world-models/tree/feat/mega-model-registry/research/runs/wm-xct-011"},"provenance":{"origin":"world-models research","builtFrom":["models/wm-xct-011-identifier-scheme/spec.yaml","ver-cy/world-models/card-supplements/wm-xct-011-identifier-scheme.json"],"providers":["Claude","Grok"],"researchStatus":"reviewable-draft","generatedAt":"2026-08-22T15:54:31Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"not-applicable","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"interaction.properties":"Institutional or informational subject: no invented physical properties.","_supplement":"Sections authored in card supplement 1.0.0 by Claude (Opus 5.5) (2026-10-05, unreviewed). Written from the published specification and established practice in the field; no new sources were read. Unreviewed."},"score":1.0}}