I understand about variables but am a bit confused as to where they are actually defined. For example, if I have a variable called PSS with a bit (1 or 0) to indicate if the item is on or off - I know how to use that variable in say a macro. But where do I actually DEFINE that variable? Do I just make a new device, a separate page under a current device or what? If I just include the definition within a macro string and set the bit, is the bit then defined to be set by the entire string of commands before it - or just by the single command before it (which is why I am unceratin of including the variable definition within a string)?

Thanks for helping a newbie MX programmer...

You define it the first place you use it. That can either be in the definition of a variable type macro or within a macro where you set its value. The list of varibles always includes a "New Variable" option.

In the Macro window select varaiable icon and the Variable window will open. In the Select Variable drop down list there is an item "New Variable" which, when selected, will open a window to define the new variable.