Here's a ham radio application of where a zeroing function would simplify a process:
Let's say you are building a vertical array for 40 meters - two vertical antennas, separated by some distance and with each vertical fed out phase with respect to the other one. You could zero the VNA on one vertical (and call it your 'reference" element) and then, when measuring the phase of the other element, you would be reading the delta between the two, which is what you care about, rather than absolute values.
For only two elements, it's easy enough to subtract one from the other so not a big deal. The software is great as it is!
John AE5X
