! PT, PTA, PTB expansion for external symbols. start: pt externalsym1 + 40,tr5 pta externalsym2 + 44,tr4 ptb externalsym3 + 48,tr3 pt/u externalsym4 + 52,tr5 pta/u externalsym5 + 56,tr4 ptb/u externalsym6 + 60,tr3