{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.user-identifier","code":"thing-q818371","url":"https://ver.cy/models/thing/q818371/","name":"user identifier","alternateNames":[],"kind":"thing","status":"published","version":"0.2.0-wave.3","language":"en","classifiers":{"family":"Thing Registry","category":"Cross-cutting context","entryKind":"thing","plane":"XCT","domain":["XCT.QTY"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"A non-negative integer used in Unix-like operating systems to identify a user account within the relevant system or identity namespace; a user identifier, or UID, supports access control, file and process ownership, and auditing, and its handling raises privacy and security considerations.","purpose":"Let an agent explain numeric Unix-like user identifiers, relay UID conventions and reserved ranges from public documentation, describe their roles in access control, ownership and auditing, and relay privacy considerations.","scope":{"in":[],"out":[],"boundaries":[]},"distinguishingFeatures":["Uniqueness within a system","Non-negative integer form","Access control role","Privacy sensitivity"],"structure":{"bundles":[{"id":"understand","name":"Understand","description":"What a user identifier is.","layers":[{"id":"definition","name":"Definition","description":"Definition.","findings":[{"id":"definition-finding","name":"Definition","description":"Definition.","questions":[{"text":"What is a user identifier, and what forms does it take?","kind":"definition"},{"text":"Is the question about a user ID, a username, a session ID or a device ID?","kind":"boundary"}]}]},{"id":"unix","name":"Unix","description":"Unix UIDs.","findings":[{"id":"unix-finding","name":"Unix","description":"Unix.","questions":[{"text":"How do Unix UIDs work, including root, system ranges and mapping to names?","kind":"definition"},{"text":"Which entry fits Unix user management?","kind":"action"}]}]}]},{"id":"use","name":"Use","description":"Uses.","layers":[{"id":"access","name":"Access","description":"Access control.","findings":[{"id":"access-finding","name":"Access","description":"Access.","questions":[{"text":"How are user IDs used for permissions, ownership and auditing?","kind":"provenance"},{"text":"Which references are standard?","kind":"provenance"}]}]},{"id":"data","name":"Data","description":"Data linking.","findings":[{"id":"data-finding","name":"Data","description":"Data.","questions":[{"text":"How do applications use user IDs as keys, and how are federated identifiers handled?","kind":"provenance"},{"text":"Which entry fits OpenID Connect?","kind":"action"}]}]}]},{"id":"protect","name":"Protect","description":"Privacy and security.","layers":[{"id":"privacy","name":"Privacy","description":"Privacy.","findings":[{"id":"privacy-finding","name":"Privacy","description":"Privacy.","questions":[{"text":"When are user identifiers personal data, and how should they be protected?","kind":"provenance"},{"text":"Which sources are cited?","kind":"provenance"}]}]},{"id":"security","name":"Security","description":"Security.","findings":[{"id":"security-finding","name":"Security","description":"Security.","questions":[{"text":"What security issues arise from predictable or exposed user IDs, in general terms?","kind":"provenance"},{"text":"Which entry fits identity and access management?","kind":"action"}]}]}]},{"id":"context","name":"Context","description":"History and design.","layers":[{"id":"history","name":"History","description":"History.","findings":[{"id":"history-finding","name":"History","description":"History.","questions":[{"text":"How did user identifiers develop with multi-user operating systems?","kind":"provenance"},{"text":"Which entry fits the history of Unix?","kind":"action"}]}]},{"id":"design","name":"Design","description":"Design choices.","findings":[{"id":"design-finding","name":"Design","description":"Design.","questions":[{"text":"What are the trade-offs between sequential, random and opaque identifiers?","kind":"provenance"},{"text":"Which entry fits identifier design?","kind":"action"}]}]}]}]},"agentConduct":{"may":["Use Unix-like UIDs to enforce access control in systems the agent administers.","Check that UIDs are unique and not reused for different accounts without review.","Explain how numeric UIDs work in Unix-like operating systems."],"mustNot":["Change a user identifier to gain or grant privileges without authorization.","Link identifiers across systems to track a person without consent or legal basis.","Expose user identifiers in public logs or URLs where they help attackers.","Reassign an identifier in a way that hands one user's files or data to another."],"requiresHuman":["Deleting, merging or reassigning user accounts and their identifiers requires human involvement."]},"ethics":{"considerations":["Identifiers tie actions and data to people, so they are personal data and a privacy risk when linked.","Mistakes in identifiers can give the wrong person access to private data."],"affectedParties":["Account holders","System administrators","People whose data a system holds"]},"owners":{"steward":"The operator of the system that issues it.","roles":[],"masterSystems":[]},"relations":[{"target":"Q28920052","type":"parent","note":"registry parent class"},{"target":"Q6545185","type":"parent","note":"registry parent class"},{"target":"non-negative integer","type":"related","note":"in registry terms"},{"target":"unique identifier","type":"related","note":"in registry terms"},{"target":"user account","type":"related","note":"in a system"},{"target":"access control","type":"related","note":"and ownership"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.user-identifier","Wikidata: Q818371 (https://www.wikidata.org/wiki/Q818371)","POSIX: uid_t user ID type"]},"properties":{"applicability":"not-applicable","items":["Unix root UID: 0 value","typical regular user UID start: 1000 value - many Linux distributions","UID range: 0 to 4294967295 values - 32-bit"]},"recognition":{"applicability":"optional","items":["A UID is a numeric account identifier in a Unix-like operating system.","It can identify a human user's account or a service account within the relevant system or identity namespace.","Usernames are human-readable names, session IDs identify sessions, and device IDs identify hardware.","Not a visible object; a number or string in system records."]},"capabilities":{"applicability":"required","items":["explain forms and conventions","relay Unix UID rules","describe uses","relay privacy considerations"]},"hazards":{"applicability":"required","items":["UID collisions across systems","Exposure of identifiers enabling tracking","Confusing identifiers with usernames"]},"interfaces":{"applicability":"required","items":["POSIX specifications for user IDs","Data protection laws treating identifiers as personal data","Identity standards such as OpenID Connect"]},"context":{"applicability":"required","items":["Uniquely identifying a user in a system.","Unix and Linux UIDs including root and system ranges","Windows security identifiers as an analogue","database and application user IDs","web service account identifiers","federated identifiers such as OpenID subject identifiers"]}},"sources":[{"title":"Wikidata item Q818371: user identifier","url":"https://www.wikidata.org/wiki/Q818371","note":"identity and sense of the item"},{"title":"Wikipedia: User identifier","url":"https://en.wikipedia.org/wiki/User_identifier","note":"general description of the item"}],"openQuestions":["Should Unix UID be a separate entry?","How should POSIX and identity standards be linked?","How should privacy guidance be linked?"],"resources":{"spec":"/models/things/publications/thing-q818371/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q818371/spec.json"],"providers":["Claude"],"researchStatus":"unreviewed","generatedAt":"2026-09-13T02:31:45Z","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":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-07T10:10:32+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass","interaction.properties":"Plane XCT: no invented physical properties."},"score":1.0}}