public synchronized void add(int op,Attribute attr){
  Modification mod=new Modification(ModificationType.valueOf(op),attr);
  modifications.add(mod);
}

public synchronized void add ( int op , Attribute attr ) { Modification mod = new Modification ( ModificationType . valueOf ( op ) , attr ) ; modifications . add ( mod ) ; }
specifies another modification to be added to the set of modifications .
