VOunits draft

[Steve Allen]

On Mon 2009-05-25T08:23:23 +0200, Hervé Wozniak hath writ:
> (not the worst case anyway but maybe other readers can find more
> difficult cases, especially those including a physical constant; and
> this depends a bit on the number of significant digits in the original
> data).

Consider the issue of AU vs. m
AU is not SI.  m is SI, but beware

1 AU = 149597870691 m in TDB/TT units ("not SI" units according to IAU comm 52)
1 AU = 149597870795 m in TCG units (IAU recommended for vicinity of earth)
1 AU = 149597873011 m in TCG units (IAU recommended for solar system)

Every application I know currently uses the "not SI" TDB/TT units.

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