How to enforce a pattern on complexContent?

[Swaroop Kumar]

Hi:

Here's a problem that's been vexing me for a couple of days now. I
need to represent a structure in which an element can either:

1) contain text conforming to a certain pattern (regex) OR
2) contain an element that contains text conforming to the same
pattern mentioned above.

My first question is, can this be done in schemas? If so, can you give
me some tips/pointers on how I would accomplish this? I've tried it
using various methods, but none of them work. I'd really appreciate it
if somebody would respond with their thoughts on this.

Thanx in advance,
Swaroop