&ND v2

+++document/meta
schemaVersion = "1"
id = "measurement-reference"
title = "Appendix — Informative Reference: Measurement Labels"
description = "Informative reference for common unit and measurement-system labels used alongside convention attributes."
family = "conventions"
group = "Informative Convention Appendices"
standing = "official"
lifecycle = "draft"
normativity = "informative"
license = "CC0-1.0"
path = "specification/conventions/measurement-labels-reference"
order = 100
publish = true
keywords = ["AEON", "measurement", "units", "systems", "labels", "reference"]
related = ["aeon-gp-measurement-v1"]
+++


# Appendix — Informative Reference: Measurement Labels [# appendix-informative-reference-measurement-labels]

This appendix provides a [* non-exhaustive reference] of commonly used measurement labels that may appear with the
[$ unit] and [$ system] attributes defined by AEON GP Measurement v1.

This list is [* informative only].
AEON GP Measurement v1 does not restrict or validate the values of these attributes.

Schemas, profiles, or processors may define stricter requirements if needed.

---


## Measurement Attributes [# measurement-attributes]


### [$ unit] [# unit]

Identifies the measurement label.

Example:

~~~$
distance@{unit="m"} = 3
~~~$


### [$ system] [# system]

Declares the measurement system or standard associated with the unit.

Example:

~~~$
mass@{unit="oz", system="avoirdupois"} = 12
~~~$

---


## Example Measurement Systems [# example-measurement-systems]

| System           | Description                                      |
| <--              | <--                                              |
| [$ metric]       | International System of Units (SI)               |
| [$ imperial]     | British Imperial measurement system              |
| [$ US-customary] | United States customary measurement system       |
| [$ avoirdupois]  | weight system used for most everyday mass units  |
| [$ troy]         | precious metal weight system                     |
| [$ display]      | display, screen, and raster coordinate context   |
| [$ css]          | CSS layout and styling unit context              |
| [$ typographic]  | typography and font-relative measurement context |
| [$ print]        | print and physical output resolution context     |
|~ Example measurement systems

---


## Example Units (non-exhaustive) [# example-units-non-exhaustive]


### Length [# length]

| Unit     | Typical system          |
| <--      | <--                     |
| [$ mm]   | metric                  |
| [$ cm]   | metric                  |
| [$ m]    | metric                  |
| [$ km]   | metric                  |
| [$ in]   | imperial / US-customary |
| [$ ft]   | imperial / US-customary |
| [$ yd]   | imperial                |
| [$ mile] | imperial / US-customary |
|~ Length units and typical systems

Example:

~~~$
length@{unit="cm", system="metric"} = 25
~~~$

---


### Mass [# mass]

| Unit        | Typical system |
| <--         | <--            |
| [$ g]       | metric         |
| [$ kg]      | metric         |
| [$ oz]      | avoirdupois    |
| [$ lb]      | avoirdupois    |
| [$ troy oz] | troy           |
|~ Mass units and typical systems

Example:

~~~$
weight@{unit="kg", system="metric"} = 82
~~~$

---


### Volume [# volume]

| Unit       | Typical system          |
| <--        | <--                     |
| [$ ml]     | metric                  |
| [$ l]      | metric                  |
| [$ fl oz]  | US-customary            |
| [$ pint]   | imperial / US-customary |
| [$ gallon] | imperial / US-customary |
|~ Volume units and typical systems

Example:

~~~$
volume@{unit="ml", system="metric"} = 500
~~~$

---


### Display and Typography [# display-and-typography]

Display-oriented units often depend on a rendering context. For example, [$ px] may mean a CSS reference pixel, a raster
image pixel, or a device pixel depending on the surrounding profile or schema.

| Unit     | Typical system      |
| <--      | <--                 |
| [$ px]   | display / css       |
| [$ em]   | css / typographic   |
| [$ rem]  | css / typographic   |
| [$ pt]   | typographic / print |
| [$ pc]   | typographic / print |
| [$ vw]   | css                 |
| [$ vh]   | css                 |
| [$ dpi]  | print / display     |
| [$ ppi]  | display             |
| [$ dppx] | css / display       |
|~ Display and typography units

Examples:

~~~$
canvasWidth@{unit="px", system="display"} = 1280
fontSize@{unit="rem", system="css"} = 1.25
outputResolution@{unit="dpi", system="print"} = 300
~~~$

When the distinction matters, a schema or profile should define whether [$ px] refers to CSS reference pixels, raster
pixels, or device pixels.

---


## Precision Example [# precision-example]

Precision may be used to indicate measurement resolution.

~~~$
distance@{unit="m", system="metric", precision=0.01} = 3
~~~$

This indicates the value is measured to [* centimeter precision].

The attribute does not require rounding or formatting.

---


## Notes [# notes]

This appendix exists only to illustrate [* common measurement labels].

It does not:

- restrict the [$ unit] attribute
- define an official unit registry
- require a specific measurement ontology

Profiles or schemas may define stricter unit lists if required.

---