group vs. Element type

[Frank G]

I'm trying to understand how to design/model data correctly in XML. I
found one site that helped a little xlmpatterns.com but it was a little
weak and used DTD's in stead of schema in most examples.

The one things that I'm trying to understand how to do is what too do
when I have a collection of elements/attributes that need to be tagged
on various elements throughout the schema. I can create it as a complex
type or a group. Both of witch seem to work but not sure what is good
practice etc.

Any thoughts or pointers to good docs on modeling/design would be
appreciated.

Thanks,

Frank