fin
Enable an agent to recognise a fin, record its attachment and condition, and judge its role in propulsion, stability or control within a surrounding fluid.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
recalled by Codex without web access - no source was read
Researched by: Codex
Purpose and description
Enable an agent to recognise a fin, record its attachment and condition, and judge its role in propulsion, stability or control within a surrounding fluid.
A fin is an external appendage of an aquatic animal, typically flattened and supported by skeletal elements or connective tissue, that contributes to propulsion, stability, steering or other specialized functions.
It can be Identify a fin's host, location and likely functional role while recording uncertainty.; Measure its exposed outline and orientation using an explicit reference frame.; Observe its movement and deformation through a relevant operating cycle.; Inspect its surface, supports and attachment for loss of integrity.; Assess whether a manufactured fin can be deployed, adjusted or replaced using documented constraints.; Refer biological injury or unresolved operating limits for appropriate specialist assessment..
Distinguishing features
Look for a projecting surface whose identified role involves interaction with surrounding water or air, rather than assuming every thin projection is a fin.
Determine whether the surface belongs to a biological body or a manufactured assembly; similar shapes do not establish equivalent structure or permissible handling.
Check how it moves: a fixed stabilising surface, an oscillating propulsive surface and a deflectable control surface require different fin descriptions.
Use anatomical or engineering context to distinguish a fin from a wing, flipper, rudder or blade; shape alone may not settle the name.
Distinguish fluid-force functions from heat-dissipation functions before applying this provisional scope.
Scope
+ Biological fins considered as functional body structures
+ Manufactured fins used for propulsion, stability or directional control
+ Fin geometry, supporting structure and exposed surface
+ Attachment to a body, hull, board, vehicle or wearer
+ Passive and actively moved operating configurations
+ Damage and restrictions affecting the fin's intended function
- The complete organism, vehicle, board or wearable assembly
- Whole-body locomotion and vehicle guidance systems
- Detailed actuator, muscle or nervous-system models
- Heat-transfer fins, pending resolution of the registry sense
- Wings, flippers, rudders and propeller blades as independent kinds; their overlap with fin requires explicit classification
- Individual product specifications and species descriptions
Characteristics
- Fin context
- biological; manufactured; unresolved Determines which structural descriptions and interventions apply.
- Host and attachment location
- host reference plus anatomical or engineering location Locates the fin and establishes the frame for interpreting its orientation.
- Functional role
- propulsion; directional stability; manoeuvring; trim; multiple; unresolved Connects observations of the fin to the behaviour it is intended to support.
- Operating medium
- water; air; other specified fluid; variable Prevents performance assumptions from being transferred between incompatible environments.
- Exposed geometry
- span and chord in m; projected area in m²; measurement convention recorded Describes the working surface and supports comparison of deployment or damage states.
- Orientation
- degrees relative to a named host axis or local flow direction Separates mounting orientation from the angle experienced in operation.
- Structural support
- observed or documented biological supports, membrane, solid structure or composite construction Explains how the surface retains or changes shape under load.
- Motion mode
- fixed; passively flexible; actively deflected; oscillating; deployable; combined Identifies whether useful action depends on motion, deformation or deployment.
- Deployment state
- exposed; folded; retracted; partially deployed; not applicable; unknown Distinguishes installed geometry from the currently available working surface.
- Surface and attachment condition
- intact; torn; cracked; deformed; eroded; fouled; loose; detached; unknown, with location and extent Supports a specific assessment of impaired function and permissible use.
Also called
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.fin-animal
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 5 bundles · 9 layers · 13 findings · 23 questions.
Fin identity and boundary Establishes which sense of fin applies and where the fin ends within its host.
The name alone does not distinguish biological structures, manufactured flow surfaces and thermal projections.
Fin sense
Records the evidence supporting classification as a fin in the provisional fluid-interaction scope.
Context-supported identification
Treat identification as a claim supported by anatomical, engineering or usage context.
- What evidence identifies this structure as a fin, and does that evidence describe a biological or manufactured structure? definition
- Does the term refer to a fluid-force surface, a heat-transfer projection or another sense? boundary
Host and part boundary
Locates the fin and separates its own structure from neighbouring parts.
Fin root and host
Record the host, attachment region and convention used to delimit the fin.
- Which organism or manufactured assembly carries the fin, and where is its root or attachment? boundary
- Are supporting tissues, mounting hardware and movable joints included in this fin description or owned by adjacent models? boundary
Working surface and support Describes the exposed shape and the structures that maintain or alter it.
A fin's outline alone cannot establish how much working surface is available or how it behaves under loading.
Fin geometry
Captures dimensions and orientation without assuming a rigid or permanently exposed surface.
Exposed outline
Record the fin's measured outline in a specified deployment and loading state.
- What are the fin's span, chord and projected area, and how were their boundaries defined? measurement
- In what deployment, posture and loading state were those dimensions measured? measurement
Fin support and flexibility
Identifies how the fin carries load and which parts can deform.
Shape support
Distinguish the exposed surface from its supports and record observed flexibility.
- What tissues, rays, spines, membranes or manufactured members support this particular fin? definition
- How does its shape change under a documented load or observed operating condition? measurement
Fluid role and motion Relates the fin's function to local flow, orientation and movement.
Fixed stabilisation, active control and oscillating propulsion cannot be assessed through the same operating assumptions.
Functional contribution
Records the fin's attributed contribution and the conditions under which it is supported.
Role in flow
Keep intended function distinct from demonstrated effects on the host.
- Is this fin used for propulsion, stability, manoeuvring or trim, and what observation or documentation supports that role? provenance
- For what fluid, relative flow conditions and host posture has that contribution been observed or specified? measurement
Fin motion and deployment
Describes fixed, flexible and actively moved operating configurations.
Available fin configurations
Record how the fin changes orientation, exposed area or shape, including the source of movement.
- Is the fin fixed, passively deforming, actively moved or deployable, and what produces that movement? definition
- What orientation range, deployment range or oscillation pattern is observed or documented? measurement
- Which configuration changes can an agent perform under the host's operating instructions? action
Fin integrity and intervention Connects damage to lost working surface, altered motion and appropriate intervention.
A fin can remain present while damage to its surface or root changes its functional contribution.
Surface and root integrity
Assesses the working surface and attachment as distinct sites of impairment.
Localised fin impairment
Locate damage or obstruction and record its extent without assuming a functional consequence has been proved.
- Where are tears, cracks, deformation, fouling or missing surface present, and how much of the fin is affected? measurement
- Is the root or mounting secure, and does observed movement indicate intended articulation or unwanted looseness? measurement
Fin-specific response
Determines what action is justified for the identified fin context and observed condition.
Permitted response to impairment
Tie continued use, adjustment, repair or referral to evidence specific to the fin and host.
- What documented criterion or specialist assessment determines whether this fin's condition restricts movement or operation? provenance
- Given the biological or manufactured context, is observation, restricted use, adjustment, repair, replacement or specialist referral appropriate? action
- What inspection or functional observation would establish that the chosen intervention restored the required fin condition? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- No sense is recorded; this description assumes the biological meaning. The PHY.OBJ domain alone does not distinguish it from engineered fins.
- The six listed kinds describe common fish anatomy and are not present in every species.
- Fin dimensions, supporting tissues and specialized functions vary widely; no universal typical measurement range is supplied.
- Which of these check these first hold for the sense of fin this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Dorsal fin
- Caudal fin
- Anal fin
- Pectoral fin
- Pelvic fin
- Adipose fin
- Which of these kinds and varieties hold for the sense of fin this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Generating thrust during swimming
- Controlling direction and body orientation
- Stabilizing the body against unwanted rotation
- Braking and maneuvering
- Supporting species identification through fin position, shape and ray counts
- Which of these real-world use hold for the sense of fin this model covers, and on what evidence? provenance
Failure modes and hazards
Recalled without web access and unsourced; every item is a lead to verify.
- Injury or loss can impair swimming performance, depending on the fin and species.
- Infection can damage fin tissue.
- Fin spines in some species can cause puncture wounds; some also deliver venom.
- Which of these failure modes and hazards hold for the sense of fin this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- flipper - A flipper is a flattened swimming limb, especially in aquatic tetrapods; the terminology overlaps with fin in ordinary usage.
- tail - The tail is the posterior body region; a caudal fin is a distinct structure associated with that region.
- engineered stabilizing fin - An engineered fin is a manufactured surface used to influence motion through a fluid rather than an anatomical appendage.
- heat-transfer fin - A heat-transfer fin increases the surface area available for heat exchange rather than primarily supporting locomotion.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of fin this model covers, and on what evidence? provenance
What the second pass must settle
- Does vr.tr.fin designate a biological appendage, an engineered fluid-force surface, a heat-transfer fin or a broader concept?
- Does an existing Vercy world model already own the intended concept, requiring a registry link instead of a separate model?
- Which registry boundaries distinguish fin from flipper, wing, rudder, skeg and swimming fin without creating duplicate models?
- Which anatomical references or engineering sources establish the relevant fin subtypes and their supported functional roles?
- Which measurement conventions, operating limits and condition criteria apply to the intended subtype, and where must they remain host-specific?