length
Let an agent handle length with unit, method, uncertainty and what is measured, and separate it from distance between points.
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.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent handle length with unit, method, uncertainty and what is measured, and separate it from distance between points.
The measurement of the extent of something along its greatest dimension, or of a line or path, measured in metres; also used for specific lengths such as calibre or eye axial length.
What it is for: Describing size and fit, in engineering, trade, medicine and daily life.
It can be measure it, with rulers, callipers, lasers; convert units; specify tolerances; compare sizes.
Distinguishing features
Extent of an object or line
Base SI quantity
Distance is length between points
Specialised lengths have domain definitions
What it looks like
A number with a length unit on drawings, labels and instruments.
Physical character
SI unit: metre m - defined via the speed of light
How it is recognised
Values in m, mm, in, ft
Dimension lines on drawings
Specialised lengths such as calibre
Related models
is a kind of - base quantity
has kind - between points
is measured in - SI unit
relates to - arc length
In practice
Families and kinds
object length
path length
diameters and calibres
anatomical lengths such as eye axial length
Identifiers
SI unit symbol m metre
Standards and regulation
SI Brochure
ISO 286 tolerances
Legal metrology rules for measuring instruments
Failure modes and hazards
Unit confusion
Missing tolerances
Measurement at the wrong temperature for precision parts
Also called
+85
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.length-attribute
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Definition What length is meant.
Which dimension is measured must be clear.
Dimension
Which extent.
Dimension
Which dimension.
- Which dimension of the object is measured? definition
- Between which reference points? definition
Domain definition
Calibre, axial length.
Domain
Domain-specific definition.
- Does a domain define this length specially? provenance
- Which standard? provenance
Measurement How measured.
Method sets accuracy.
Instrument
Tool.
Instrument
Instrument used.
- Which instrument measured it? provenance
- Is it calibrated? provenance
Uncertainty
Error.
Uncertainty
Measurement uncertainty.
- What is the uncertainty? measurement
- At what temperature was it measured? measurement
Units Units and conversion.
Unit errors cause failures.
Unit
Stated unit.
Unit
Unit used.
- In which unit is it given? definition
- Could it be misread? boundary
Conversion
Exact factors.
Conversion
Conversion factors.
- What is it in metres? measurement
- What rounding was used? measurement
Specification Tolerances.
Specifications need tolerances.
Tolerance
Allowed variation.
Tolerance
Tolerance band.
- What tolerance applies? measurement
- Is the part within it? boundary
Fit
Matching parts.
Fit
Fit between parts.
- Will the parts fit together? boundary
- Which fit class is specified? provenance
What the second pass must settle
- Should specialised lengths be separate entries?
- How should tolerances be recorded?
- The registry entry has merged aliases such as ammunition calibre; how should they be linked?