// if no master is found, then create a new AttPool.
{
ReferenceExp[] combines = combinedAttPools.getAll();
for ( int i=0; i<combines.length; i++ ) {
AttPoolClause ac = module.attPools.get(combines[i].name);
if( ac!=null ) {
// ac.exp==null means no master is found but someone
// has a reference to this clause.
// this is OK.
if( ac.exp==null ) ac.exp=Expression.epsilon;