Tried searching, saw one post but there was no definitive answer was given.

I'm in process of replacing my Alternator, and when I was about to reinstall the new one I noticed this hose just hanging there. Its a hard pvc type line. Guessing a Vent tube or maybe a vacumn line. Both ends were disconnected.

Will attach a couple pics. Really wanting to figure this out so I can get this ALT back in. Worried its an important piece lol

Looks like DIN 73378-8xi>pa12-hl-rss-de-normaflex-bmw-31.50-1.428.849-21/08/03-05:42:56-# is the stamp on it?

Thanks ahead of time