Global variables

It is best to use one compound variable for all global variables of your 
program. 
Why? Because then you need only the stem of this compound variable in the 
variable list for the option <EXPOSE to make all global variables known to 
the procedures declared with <PROCEDURE -- regardless of how many global 
variables you define. 
And if you define some more global variables whit this same stem while 
developing your program, they will automatically be known to all 
procedures.