HP 3000 Manuals

Introduction to MPE XL for MPE V Programmers Migration Guide

CM and NM Trap Handler Differences 
(changed) 

A user-created CM trap handler differs from a NM trap handler in its
calling sequence and the method by which the trap handler obtains error
information:

 *  In CM, typically, error information is obtained by the trap handler
    from the process stack.

 *  In NM, a pointer to a record containing error information is passed
    to the trap handler.

MPE/iX 5.0 Documentation