what hapens with successive substep relative extrusions?

Are sub step size quantities of extrusion simply ignored (when using relative extrusion) or does the firmwhere have a running total of these and it will for example output a step of extrusion for every ten tenths of step?

It keeps a running total of the fraction of a microstep that is outstanding, until it reaches a whole microstep. But this wasn't working properly until firmware version 2.02/1.23.

Thanks.
What is the minimum resolution that it would handle well?
Not asking on the back of a fault, I just got the parser to kick out a warning message for submicrostep sized extrusions and it almost looked like the program was stuck in a loop dumping out hundreds of warnings for moves from a standard height Benchy build.

Just cleaned up the parser a bit and the number of short vectors is a small percentage of the total numbers of moves. Extrapolating further still it is likely that the total length of these vectors will be an even smaller fraction of the total distance travelled by the nozzle.
Catching the fault was a good effort! I'm guessing it came from the multicolour work rather than observed build issues on single material extrusion?
Edit:
Total moves: 109178
Vectors shorter than one microstep (16 microsteps)
Small x vectors: 13
Small y vectors: 0
Small z vectors: 0
Small e vectors: 700Vectors shorter than one physical stepper step
Small x vectors: 248
Small y vectors: 0
Small z vectors: 0
Small e vectors: 69174Vectors shorter than one physical stepper step (if I swapped for 0.9 steppers)
Small x vectors: 115
Small y vectors: 0
Small z vectors: 0
Small e vectors: 19956