David,

For AIX 4.1.3 and above, the correct file name is en_US.ISO8859-1.src. Also,
the localdef command requires the C compiler which is no longer bundled with
4.1. So now I got to install the C compiler before I can do this localdef 
command.

Just what is the rationale for throwing out the code that uses the options file?
This could just as easily have been implemented with another option to follow
the NLS standard.