HP 3000 Manuals

HP FORTRAN 77/iX Migration Guide

Integers and Logicals 

Integers and logicals can remain as originally defined or be converted to
32-bit items for improved performance.  If you convert 16-bit integers
and logicals to 32-bit items, check that equivalences, common variables,
and parameter lists match correctly.

MPE/iX 5.0 Documentation