CDC Floating point = tests?

On the old CDC machines running EKS you could use a regular if test to
see if two floating point values were equal, and it worked! I've
ported lots of code from EKS to other platforms and I've had to change
those lines of codes many many times. I'm currently doing another
upgrade to one of those programs. It would read in floating point
values with formatted read statements and compare to other floating
point values. They weren't integer values either. The code relied
heavily on this and it worked fine. How did this work? How did the
CDC compiler handle this?

.