Brian,
 
How nice to hear from you.
 
The format differs with so many countries having their own postal systems
:-).  For imstance, in Canada the postal code should be on the last line, in
capital letters.  Yet, most people slap it within the address block.  In
Germany, the postal code goes in before the city!.
 
If it where me, I would make the address block 10x30 and go from there.
 However, you probably want to be able to do processing on the ZIP code and
so it would be useful to have it as a seperate field.  Just remember that the
US is one of the few countries which uses an all-numeric zip code.  Most
other countries use combinations of letters and digits.
 
(This is also why the zip is pretty useless as it only gets within a very
large area, the area served by a postal station.  I remember in Canada, the
combination A#A #A# pinpoints the address to within a few blocks!.  The USPS
did expand the code with 4 extra digits, but who uses that?  Even worse who
even knows their full zip.  I have seen mine with two different +4 code!!)
 
But I digress.
 
I will be interested to see what the answers are.
 
Kind regards,
 
Denys. . .