Yosef Karo

“ Anywhere (on the lung) that the sircha is permitted, even if there is another sircha connected to that same sircha it is called a "folded sircha" and it is permissible (B"Y) . 5 If one is uncertain as to whether (the sircha) is on the back of the lobe or in the chituch and when the lungs are inflated a lot it appears that (the sircha) is in the chituch but when the lungs are not fully inflated the sircha appears to be outside (the chituch) the animal is kosher.
6 A sirkha connected from the varda lobe to anywhere is treifah, even to its own pouch and even if the whole lobe is connected to it. ”

“ And there are places where their practice is being lenient even in this, but to me it seems the first opinion (is right) , to not crush in the Varda, and any Sirkhot that are not in their order, since the Sirkha that's not in their order is treif is mentioned in the Gemara, so there's no arguing with that; there's no relying on those that say to be lenient regarding crushing and feeling (and so it sounds from the language of MHRY"V, no arguing) . ”

“ And if a Sirkha goes out from the lower parts of the lobe and spreads on the back of the Ona and is Nirsakh to the wall, if the majority of the Sirkha is on the back of the Ona it's kosher and if not it's treif. ”