diffrence between backup and forward

[Hans Vereyken]

I have a small question:
Why can the forward element contain a voice and/or staff element (a backup element can't have these)?

Thanks in advance

[Michael Good]

Hi Hans,

This is because the forward element can be viewed as an invisible rest. It is useful to assign invisible rests to a voice or a staff to follow the progress of the music per voice or per staff.

The backup element on the other hand is usually used to jump between voices or staves. So it makes much less sense to have a voice or staff element assigned to that element.

[Hans Vereyken]

I see, so when processing a forward element with voice and/or staff set it's essentially the same as a rest with print-object="no"
Thanks!