How to get UTC offset for non-standard time zone names?

[skip at pobox.com]

I have the pytz package but it doesn't know about non-standard timezone
names like "CDT5" or "CST6".  I can obviously infer that they are either
five or six hours behind UTC.  Are they constructed in some standard way so
that I can assume that if a timezone name is not known to pytz I can assume
the trailing number represents the number of hours behind UTC?  Is there
some standard definition of the format of such semi-numeric timezone names?

Thx,

-- 
Skip Montanaro - skip at pobox.com - http://www.smontanaro.net/