Input Thru... ?

JJ OS.
What does IPT (Input Thru) mean?
Its right under autoload...

Yet again im having issues with saving files, especially with Autoload. Its never worked correctly for me. Also have some very finicky pads.
Booo.

it lets you take an external input, route it through the MPC (and run it through effects if you want) and then send it independently out of the MPC through the outputs of your choosing