Syntax References represent established works of other organizations. Such works – among others - may define semantic information, topologies, a language for a code set, or dictionaries and facilitate the programmatic evaluation or the lookup of a quantity or unit e.g. in a dictionary or ontology. They may be publicly defined by standard bodies such as IEC or proprietary (e.g. vendor-specific dictionaries).

The Quantities and Unit Model provides a powerful way to relate quantities and units to such Syntax References using the Dictionary References model defined in 10000-19.

Table 33 lists Syntax References that are applied in certain markets. This list may be extended in future versions. Vendors or organizations may also specify additional Syntax References.

An overview for each Syntax Reference in this table is provided in Annex C.

Table 33 – List of Syntax References

Common Name

Syntax Reference URI

Full Name


Unified Code for Units of Measure


Quantities, Units, Dimensions and Types Ontology


Common Data Dictionary


Codes for Units of Measure Used in International Trade


LaTeX SI Unit Extension