key and keyref matching in xsd 1.0..

I know that data types must match for 'key' and
'keyref' xpath 'fields'. Should they match in terms of
'element' or 'attribute' type as well?

i.e. say I have attributes 'a', 'b', and element 'c'
in the selector 'fields' of key definition. Should I
also have 2 attributes and 1 element of same data
types (of Key) in the 'keyref' as well? OR can I mix
and match (i.e. can I map these 2 attrs in Key to 2
elements in keyref?).

-D


      ____________________________________________________________________________________
Be a better pen pal. 
Text or chat with friends inside Yahoo! Mail. See how.  http://overview.mail.yahoo.com/