In ACF/TCAM, a user-defined routine that processes messages being received by the message control program from a logically attached, BSC, SS, or SNA station.; 在遠程通信存取方法高級通信操作程序(ACF/TCAM)中,負責處理報文控制程序所收報文的 用戶定義程序。這些報文均來自局部連接的BSC(二進制同步通信)、SS(啟停傳輸)或SNA站。