If you have global vars, then have a global event sheet with events for those vars
create a new event sheet named "global" containing
always: set global('asdf') to clamp(global('asdf'),0,10)
then include that sheet in every layout's global sheet.
You have now a centralized place where to set your maximum and minimum for these global variables, and the regular variables that do not need clamping are unaffected =)