XRANGE([a[,b]])

This function returns a range of ascii characters in a string. If they
are supplied, a and b must be single characters. The defualt values for
a and b are '00'x and 'ff'x respectively. The result is a string
consisting of ascii characters in sequence starting with a and ending
with b. If a>b then a string of (b-a+257) characters is returned,
starting at a and ending at b, wrapping around from 'ff'x to '00'x.

UNIX Specific Functions:

The following functions are built into this version of REXX, although
they are not standard REXX functions. Most of these functions appear in
the literature.

NOTE: many of these functions which accept string arguments will ignore
      any characters after (and including) a "00"x character.