A process can either enter or initiate an imported procedure.

If a process enters an imported procedure, the procedure is executed on the process stack of the importing process, rather than the process stack of the library that exported the procedure.

If a process initiates an imported procedure, the procedure must run as a dependent process. The system creates a new process stack to execute the procedure. The resulting process is considered an external process. (For information about external processes, refer to Understanding Interprocess Relationships.)