VOUnits RFC

[Frederic V. Hessman]

How about:

	units
		: fits_units
		| unknown_unit_string
		| ...
		| scalefactor + ' ' + units
	scalefactor
		: floating_point_literal

(where floating_point_literal CAN use the 'd', 'e', 'D' and 'E' forms but SHOULD use just 'e' when not a simple integer or float) and state that

	- the above formal grammar can be found at …
	- applications MUST handle unknown_unit_string and scalefactors without bombing
	- applications SHOULD attempt to look up unrecognized unknown_unit at some knowable vo resource for such info
		- a minimal unit vocabulary service will be provided by IVOA at … via ….
			- the corresponding translated scalefactor and standardized units for further numerical manipulations will be provided in the form ….
			- this is the way to load your units parser with this information up front: ….
	- VOTable unit metadata SHOULD be encapsulated in the document via …
	- applications SHOULD attempt to keep track of unit metadata when encountered and pass it on with little or no manipulation/alteration

Rick