6 reasons why milking a cow on Shabbos is asur-Parshas Hashavua

Milking a cow on Shabbos,

Why not?
6 different reasons, probably no other מלאכה,  do we have a six way מחלוקה to which אב מלאכה it belongs to.

מפרק(דש)               Rashi Shabbos 95a

קוצר                      Yerushalmi Shabbos 7 :Hl 2

ממחק                   Tosfos Shabbos 73b

בורר                      Rashbo Shabbos 144b

טוחן                      Yeraim # 274

גוזז                       Tosfos Rosh Shabbos 95a