Adding/Editing Memory VariablesTo create a Memory Variable, click the "Add..." button on the Memory Variable Table. This will open a new pane with space to enter a System Name and User Name for the new Memory Variable, plus and "Add" button.
You must enter a unique System Name. System Names for Memory Variables have no set pattern. You can call them whatever you want. There's a weak convention of starting them with "IM" for "Internal Memory", but that's not required.
The User Name is optional, but if given has to be unique.
Back to the Memory Variable Table help page.