Fortran dim(x,y), to what end?

Question

In Fortran dim(x,y) returns the difference x-y if the result is positive; otherwise returns zero. What was it intended to be used for? What is the meaning behind the name dim?

Answer 1

Presumably it comes from dimension, i.e., the length, width, height of something. Since none of these values can be negative it's calculated as the positive difference.