"REXX has no reserved words. Words are only reserved in context.
Hence: 
 
  if=1
  if if then
    then=2;
  else
    else=7
  do forever=3 to 7 until end;
    end=1;
  end
parse var x with var with left right value
are all valid instructions. A function is recognised solely by the presence of a '(' appearing immediately after it, not by the spelling of its name.
This is where Rexx has a big advantage over things like Visual BASIC. (I was typing a BASIC program the other day, and the first three variable names I tried were all keywords...)"
Source: Ian Collier (see EMail Addresses)