From: Georg S t a n a Message: 15042 Date: 2002-09-03
>Perhaps the variant <zãu> is due to a slightly labialized pronunciation
>of initial /(d)z/?
Could be. Anyway, the form with -dz- (as well in other words, such
as "dzice", "dziua"/"dzîua") are attested in numerous documents. And
is still in use in the regions I mentioned in a previous post.