Unified Codes for Units of Measure (UCUM)
This standard is becoming recommended practice for various organizations, for example some of the OGC standards.
The links provide the following:
- a Java applet/web interface to convert among many units in different unit systems,
- references to the tables of units in those different unit systems,
- links to software implementing the UCUM units system,
- the Java documentation for the software, and
- a nice explanation of all of this material.
This is an extremely comprehensive and carefully structured approach to documenting and exchanging units of measure. It references several other standards, upon which it draws extensively, and describes the ways in which it improves upon those standards.
The home page also includes an extended and eminently reasonable discussion of the pros and cons of different unit systems. This is good reading if you need to understand how to pick a particular representational system.
Some changes are still contemplated, but the core set of units and their representations is stable and thoroughly specified.
