pattern values

[c_capatana@hotmail.com]

I have to write an schema for application that must run on Win and
Unix.

I have to describe some pattern values. I have read some documentation
and some previous Q&A in XML groups. Some questions remain for me.
What's the
better way to use for specifying these pattern value, independent of
platform:

for digits: [0-9] or \d
for example 12 digits pattern must be: [0-9]{1,12} or \d{1,12}
for enter: &#xD or \n
for example an element that must contain 12digits Enter 15a:
\d{1,12}
[A-Z]{1,15} or \d{1,12}\n[A-Z]{1,15}

Are both definitions correct. What is preffered?

Please help me.
Thanks.