Currently all functions used in surface variable loading are continuous.
Multiple or discontinous functions can be applied by splitting the surface. For example, applying wind pressure to a cylindrical object like a tank requires two functions to apply pressure around the full circumference. A simpler and more flexible option would be to include an IF statement in the available surface variable functions. Even better would be a multi-line description (or 3 way IF) of a surface variable load to apply patch loads or functions that can be turned on and off.
e.g. A patch load or temperature could be applied by say.
x < x1 then zero
x1<x<X2 the some value or function
x>x2 then zero or some other function