defines how to calculate one unit of measure in terms of another. indicates a source unit of measure that is to be converted into another unit indicated in toUnit. the target unit of measurement for a conversion from a source unit referenced in fromUnit.

The conversion element is designed to store information about converting from one unit of measurement to another. The formula attribute holds an XPath expression that indicates how the measurement system in fromUnit is converted to the system in toUnit. Do not confuse the usage of the dating attributes (from and to) in the examples with the attributes (fromUnit and toUnit) designed to reference units of measure.