I was experimenting with Units.xml. I changed the default length unit to feet and adjusted the conversion factors accordingly. It seems to work. Some unit entries have base="true" to make them the base unit. When I got to volume the base was L (liter). Now each entry has a description="xxx" where xxx is a number from 293 to 541 with some gaps. I was wondering what the descriptor means. Can I add descriptors beyond 541 or even in the gaps. I was going to make ft^3 the base volume which would mean I would have to add new unit descriptor and push liter down the list. I'm hoping this would improve the US/Imperial units conversion.