# 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 ### `unit` Identifies the measurement label. Example: ``` distance@{unit="m"} = 3 ``` ### `system` Declares the measurement system or standard associated with the unit. Example: ``` mass@{unit="oz", system="avoirdupois"} = 12 ``` --- ## 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) ### 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 | 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 | 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-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 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 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. --- --- ## Related documents - [AEON GP Measurement v1](./aeon-gp-measurement-v1.md)