How should I call an attribute within an expression function?

I am building a template that will be using a certain value many times throughout the various expressions. For example under an expression analysis:

IF TagMax('A','*-100m','*') = 1 then 1 ELSE 0

How can I edit the syntax of this formula to make the number 100 as an attribute and call it within the expression? It will be the equivalent of the following:

[x] = 100 as an attribute

IF TagMax('A','*-[x]m','*') = 1 then 1 ELSE 0