דאָס

I think דאָס can also substitute for אַז or something like כּדי (maybe daytshmerish). Here's an example from Malka Lee, Durkh kindershe oygn:

ikh vil es ufheybn funem ash... es zol nisht opgevisht vern... dos mayne kinder un kinds-kinder zoln visn zeyer opshtam.