REXX Tips & Tricks, Version 2.80

0.9b (c) 1995 Peter Childs

Compound variables

To avoid mysterious errors you should always use some special chars as 
first chars of a tail (for example two underscores __) and never use these 
chars for normal variables (or vice versa). 

Another nice method to avoid errors: Always use a number (0..9) for the 
first character of the tails. This method works because variable names 
can't begin with a number.   

Source:  I found this hint in the documentation for the DLL RXU 

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