[fitsbits] Question on angstrom and erg units in FITS standard

[Lucio Chiappetti]

On Tue, 4 Nov 2014, Arnold Rots wrote:

> I think the authors waffled on the issue, on purpose.

Can't remember whether it was done on purpose in FITS 3.0 or simply 
inherited from the previous versions.

> There are three statements that are relevant here:

> 1. FITS writers *should* use the IAU recommended SI units
> 2. Angstrom and erg are *deprecated in the IAU list*
> 3. Angstrom and erg are in a list of *allowable units*

> My interpretation is that Angstrom and erg are not deprecated in FITS, 
> but neither are they on the preferred list of units: the combination of 
> the three statements says that they are allowable, but you *should* not 
> use them (i.e., less strong than deprecated),

Given that there is no such thing as an "authenticated interpretation"
my interpretation agrees with Arnold's

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