Microsoft Patents 'IsNot'

Terry Reedy tjreedy at
Sat Nov 20 02:59:41 CET 2004

""Martin v. Löwis"" <martin at> wrote in message 
news:419E6C13.1040508 at
> Wrt. claim 3, Python is *not* prior art, because Python's operator
> is the two keywords "is not", not the single keyword "IsNot".

But, for whatever it is worth, the ref manual *does* label 'is not' as *an* 
operator.  In this context, 'is not' is a compound (key)word with a space 
(rather than a hyphen or neither).  Since English compounds can often be 
written both with and without a space or hyphen, with the choice being a 
matter of taste, the difference between 'IsNot' and 'Is Not' is rather 

> Paragraph
> [0050] elaborates that the claim extends beyond the literal spelling
> they give (e.g. to "is_not", "isnot" etc.),

And 'is_not' is the CS alternate spelling of 'is not' with ' ' changed to 
'_' (instead of '-') to indicate that the space is connective, forming a 
compound word.  In names, Python also requires, for obvious lexical 
reasons, connective spaces ('_'s).  Recognizing 'is not' as a unit requires 
a special rule; 'is_not' might have been more consistent with the rest of 
Python, but Guido was and is a keywords minimizer.  Without knowing this 
rule, one could easily parse 'a is not b' as 'a is (not b)' like Basic 

To be, this 'patent' is so absurd that I initially had difficulty believing 
to to be real and not a joke.

Terry J. Reedy

More information about the Python-list mailing list