I propose modifying the Move Absolute block to include check boxes for each axis like the following mockup:
An example of why this would be useful is when the UTM is in some unknown location and you want to zero out just the Z axis before any other movement.
This is something I wanted as soon as I started making sequences and I have seen another post asking for the same thing, but not quite in the right way.
I imagine that the block would default to having all 3 axes checked and all 3 offsets unchecked. Typing a number into any of the number fields would check the box and unchecking a box would clear the field.