[Avodah] Test your knowledge.

[SBA]

In SA YD, vol 3, immediately following siman 242, there are 2 pages with no
 SA text - but headed :"Pilpul behanhogas Horo'os Issur veHetter 
meHorav Hamechaber YZYY"A [Yud Zayin Yud Yud Alef].

I couldn't recall ever seeing this acronym previously.
And neither did almost everyone I asked.

Almost. Our local font of wisdom, Rav Shimon Opman gave 
the answer on the spot!

Nu...?

SBA