HP 3000 Manuals

MPE XL Native Language Programmer's Guide

User-Defined Commands (UDCs) 

ENTRY, FCOPY, QUERY, SORT, and MERGE are often run from within
user-defined commands (UDCs).  NLUSERLANG and NLDATALANG give the
application designer the option of establishing a native language within
a UDC.

MPE/iX 5.0 Documentation