Rav U'Shmuel In R' Yose Ben R' Yehuda (Daf 18)

I show you my tabas. The shiyur al panai killer. Then you left tiny hit al panai killer rounds. It's a crucial shita. Rebbi Yosi b'Rebbi Yehuda learns even you left away from the tabas al chot, it's also good. This is the two shitas in the mishna. Ravin Shmuel comes along in the gemara and they say Rebbi Yosi b'Rebbi Yehuda that holds that if you left a roif from the chot from the tabas al doyela it's kosher, it's only in the tabas al doyela. Any place after the tabas al doyela in the tabuas, meaning like this, in the this is the tabuas, the cartilage, you're not allowed to shecht. Rebbi Yosi b'Rebbi Yehuda Rashi says bain a tabuas between the tabuas Rebbi Yosi b'Rebbi Yehuda, you are allowed to shecht.