Great stuff, perhaps you would also like to describe how G28 can be different for cartesian vs (linear or rotary) delta, i.e. home one axis at a time vs home all axis at once?
G28 is even more convoluted in real CNC world. It doesn’t mean go to the home position, it means return to the home position from a intermediated point. So basically if you use G28 in absolute you can crash the piss out of a machine.
G90 G28 Z0; means go to Z0 then go home. That’s the spindle nose to the table with no other offsets present.
the proper way to use G28 is:
G91 G28 Z0; which means move nothing, then go home on z.
just use the machine coordinates.
G53 Z0;
Which works fine in absolute.
@John_Herrington We know about the intermediary point feature, it’s on the todo list.
@Douglas_Pearless I’ll add that, thanks.
Want me to write an M408 page 
@Chris_Brent Sure ! Just add a header saying it’s not supported yet. Where are we at with that by the way ?
That’s funny. It never was a feature, it is just how it was implemented well over 30 years ago. The null incremental movement is just a work around of the intermediate point requirement.