I have 2 holes that can be no further than 36" from each other.  I am trying to set up an equation for the dimension between them.  So far what I have is:

a=    (whatever the user types in)

b=36

c= IFF(a>b; b; a)

D4@Sketch27 = c

I can't figure out what would go in the place of so that the typed dimension can be compared to the maximum allowed value in the equation.

Thoughts?