Establishing control variables

Control variables are defined in three different ways.

$set varname value

$setlocal varname value

$Setglobal varname value

where

 varname is any user chosen variable name

 value is optional and can contain text or a number

The main difference between these definitions involves the accessibility of the control variables within code brought into a program through the family of include commands.

These variables can be destroyed using

$Drop varname

$Droplocal varname

$Dropglobal varname

where varname is as above.