Fields inside blocks

I saw a writeup on a field that gets it's value from the scale of a paperspace viewport. Is there anyway to incorporate this field into a block? What I want to do is, if possible, add this field to the callouts we use that call out what the plan is and it's scale. But I'm abit confused on how the field is linked to the viewport because the block is created prior to the viewport.

I'm not sure if you can create a block with a field and insert it into a drawing and expect the field to be properly populated. The only thing I could think would be inserting the block and running a LISP to update the field to read the viewport of your choosing. However, this would likely update all instances of said block, unless you also had that LISP create a unique name for the block you modified.

Creating a unique name is doable, but I haven't worked with fields enough to know for sure about the rest.

You could make the field a lisp variable which is set to the scale of the viewport.