The published OCX Schema

Element for describing units. Use in containers UnitSet or directly incorporate into a host schema. Unit has the following child elements:

Child	Namespace	Type	Use	Cardinality	Choice	Description
RootUnits	unitsml	RootUnitsType	opt.	[0, 1]	False	Container for defining derived units in terms of their root units. This allows a precise definition of a wide range of units. The goal is to improve interoperability among applications and databases which use derived units based on commonly encountered root units.
UnitName	unitsml	NameType	req.	[1, ∞]	False	Element containing the unit name.
UnitSymbol	unitsml	SymbolType	opt.	[0, ∞]	False	Element containing various unit symbols. Examples include Aring (ASCII), Å (HTML).

Unit has the following attributes:

Attribute	Namespace	Type	Use	Default	Fixed	Description
id	unitsml	xs:ID	req.			id (as an attribute name)
dimensionURL	unitsml	xsd:anyURI	opt.			URL to a representation of the unit or quantity in terms of the 7 SI base dimensions.