[2]It should be noted that in response to numerous comments from the FITS community, the guidelines outlined here differ significantly from those given in all version of this memo prior to 1993 May 11.

[3]Note that the IAU has ruled that a second of time should NOT be abbreviated to sec; the string sec should NOT therefore be used to specify such a quantity within a FITS file.

[4]The only exception is kilogram (kg) which represents 10³ grams. Multiples & submuotiples of mass therefore adhere to the ahove rules, but using grams, with the unit string g, as a base (hence 10⁹ kilogram denoted by Tg, 10¹⁵ kilogram by pg etc). The use of grams (g) as a unit is, of course, also allowed.