gml:catalogSymbol

For global understanding of a unit of measure, it is often possible to reference an item in a catalog of units, using a symbol in that catalog. The "codeSpace" attribute in "CodeType" identifies a namespace for the catalog symbol value, and might reference the catalog. The "string" value in "CodeType" contains the value of a symbol that is unique within this catalog namespace. This symbol often appears explicitly in the catalog, but it could be a combination of symbols using a specified algebra of units. For example, the symbol "cm" might indicate that it is the "m" symbol combined with the "c" prefix.