Karl,
There is a workaround. You can assign a character format to all or part of a variable definition by putting the character tag in angle brackets where you want to apply it. You can undo the effect of that tag with </>.
Suppose you want to define a variable to be an asterisk surrounded by spaces. Define a new character format called DoNothing that sets no properties. (It may be helpful to set all fields in the character designer to As Is with the Shift-F8 shortcut). Then define the variable to be:
<DoNothing> * </DoNothing>
--Lynne