public virtual IEnumerator GetEnumerator() {
Hashtable prefixes = new Hashtable( lastDecl + 1 );
for( int thisDecl = 0; thisDecl <= lastDecl; thisDecl ++ ) {
if ( nsdecls[thisDecl].uri != null ) {
prefixes[nsdecls[thisDecl].prefix] = nsdecls[thisDecl].prefix;
}
}
return prefixes.Keys.GetEnumerator();
}