xml schema RegEx character class

I know that [abc] can be used to match a or b or c but how can it be made to match a and b and c or indeed any permutation?

What I'm really trying to do is with words. i.e [(one)(two)(three)(four)(five)] and I need an expression that will allow, all or some of the words to be allowed?

Can this be done with Eclipse XML schema?

TY

C