Reserved Words

"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)