Provides classes representing physical quanties. The Units class defines an enumeration of physical units such as Units.hertz and Units.microseconds. It also contains a convention for identifying locations in time with units like Units.t1970, the number of microseconds elapsed since midnight, January 1, 1970. The Units class also contains a registry of Units and the conversions between them.

A Datum is a number in the context of a Unit, for example "15 microseconds.". A Datum object has methods for formatting itself as a String, representing itsself as a double in the context of another Unit, and mathematical operators that allow simple calculations to be made at the physical quantities. Also a Datum's precision can be limited to improve formatting.

A DatumRange is a pair of Datums that identify a range in the physical space of a Unit. An example of a formatted DatumRange is "January, 2005" or "0 to 50Hz."

Also there are utility classes for parsing and formatting times.