Set Environment Variable Program V2.0 (c) 25-Oct-1992 by John Wolchak.
Usage is:  SETENV <variable> <value>  or  SETENV %rce <variable> <value>
        <variable> by it's self to erase variable.
        <value> can be: '%rep<del><txt1><del><txt2><del>' text replace.
          '%chgup' or 'chglo' upper/lower case environment variable data.
          '%prompt %noecho %upper %def<del><text><del> <message>'.
             '%noecho' for no echo, '%upper' '%lower' upper/lower case only.
             '%def<del><text><del>' supply a default, '%trim' trim spaces.
             '%timo=hh:mm:ss' prompt time out, time length.
        <value> can include keys such as:   ie  setenv drivedir %drive:%cwd
          %dosv / %dosm for DOS major / minor version.
          %cwd or %cfd for current directory,   %drive for drive letter.
          %time / %daten for current time / date format 'n'.
          %+n / %-n for default drive plus / minus 'n'.
          %loc/<n>/<var>/<str>/  %len/<var>/  %sum/<var>/<n>/
          %mid/<var>/<n1>/<n2>/  %elem/<n>/<char>/<var>/  %chr/<n>/
Note:     Use %% to represent a single % in BAT files.
       SETENV return codes:             no command, help issued         00h
root environment set            01h     environment variable erased     02h
environment variable created    03h     don't know about MS-DOS V1.x    04h
environment variable updated    05h     unmatched delimiter             06h
not a valid argument            07h     environment variable not found  08h
offset drive will be invalid    09h     environment space is full       10h