measures.xsd

See ISO/DIS 19136 17.3.
gml:MeasureType is defined in the basicTypes schema.  The measure types defined here correspond with a set of convenience measure types described in ISO/TS 19103.  The XML implementation is based on the XML Schema simple type "double" which supports both decimal and scientific notation, and includes an XML attribute "uom" which refers to the units of measure for the value.  Note that, there is no requirement to store values using any particular format, and applications receiving elements of this type may choose to coerce the data to any other type as convenient.