[fitsbits] Proposed Changes to the FITS Standard

[William Pence]

Since a couple people have already questioned the proposed change to the 
FITS Standard to replace the term "twos-complement" with "two's 
complement" here is a bit more information to consider.  For what it is 
worth, this is consistent with Wikipedia which defines the term as 
"two's complement" (http://en.wikipedia.org/wiki/Two's_complement). 
Under the "discussion" tab on that page there is some justification for 
this usage.  Below is a copy of the relevant text.  Note in particular 
the explanation for the different position of the apostrophe in "ones' 
complement" and "two's complement".

Bill Pence

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"Two's" and "ones'" complements?

Searching [with Google] for twos complement and ones complement, with 
any of the three candidate punctuations, shows that the majority of the 
first page of results for any candidate punctuation are punctuated the 
way we have it: two's and ones'. My rationale is that Knuth does it that 
way, and has a good explanation for his choice, so let's follow the 
leader. But if everybody else also does it that way, that's good for us 
too. :) --Quuxplusone 06:09, 8 February 2007 (UTC)

         Detail-oriented readers and copy editors should notice the 
position of the apostrophe in terms like two's complement and ones' 
complement: A two's complement number is complemented with respect to a 
single power of 2, while a ones' complement number is complemented with 
respect to a long sequence of 1s. (Volume 2, p. 203, according to [1])
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