Start Process to Edit vs. Edit Object using Process? Why?

Jaymer

On a Grid, with a Row Operation to EDIT the row, you can either

1) Edit Object - this is simple, specify the form (or default) and a Form comes up to edit.

2) Start Process "MyEditProg" and pass the BO as context. The process could VIEW or EDIT using an appropriate Form.
3) Edit Object, specifying "Use Process".

Whats the diff. between 2 & 3 ?
When would you ever use 3?

aware_support

I vaguely remember that this is for situations when you need Prev/Next/First/Last operations to work, but editing has to be done via a process.