There are two versions of Mx in this subdirectory, one for aix 3.1
(mx_aix3.1.Z) and one for aix 3.2 (mx_aix3.1.Z).  You should grab the one
for the operating system on your rs6000 powerstation.  They are both stored
in compressed format, so make sure you transfer using binary ftp, and then

uncompress mx_aix3.2.Z
mv mx_aix3.2 mx

should give you the binary executable file mx.  If by default files ftp'd to
your machine are not executable then you will need to do

chmod +x mx

to make it executable.  It can be run using

mx < inputfile > outputfile

See the directory ~ftp/pub/mx/examples for example files.

Both versions were created November 16 1993.