The cdebconf progress bars are currently driven by the following protocol:
PROGRESS START <min> <max> <title-template>
PROGRESS SET <val>
PROGRESS STEP <inc>
PROGRESS INFO <info-template>
PROGRESS STOP
Proposed protocol, not implemented yet:
PROGRESS REGION <min> <max>
- Mark a region of the progress bar which a subsequent (nested) PROGRESS
START will occupy. Titles given to nested PROGRESS START commands will
stack, and thus previous titles will be restored on PROGRESS STOP
(details of display may depend on the frontend); PROGRESS SET and STEP
commands within the sub-bar will be mapped linearly onto the main
progress bar; info messages will not be erased when exiting a sub-bar
and are expected to be superseded by future PROGRESS INFO commands.