Learn the גמרא דף יא. “ואף ר’ יוחנן” (sixteen lines from bottom of Amud) until “ורמי” (second line from bottom of the Amud)
Topic: צורת הפתח מן הצד
What is the case?
There are multiple explanation in the Rishonim
See רש”י דף יא “מן הצד
See רבינו חננאל (on side of gemara)
See ריף
https://hebrewbooks.org/pdfpager.aspx?req=14312&st=&pgnum=329
Learn רשב”א who asks multiple questions on the explanation of the ר”ח and ריף
https://hebrewbooks.org/pdfpager.aspx?req=37275&st=&pgnum=15
According to Rashi if the top string is wrapped on the side of the pole at the top is it acceptable?
Learn ט”ז ס’ שס”ג ס”ק ד
How to we conclude l’halacha
Learn שולחן ארוך או”ח ס’ שס”ב סע’י יא
See and משנה ברורה ס”ק סד which discusses many details of צורת הפתח מן הצד
https://hebrewbooks.org/pdfpager.aspx?req=60389&st=&pgnum=54
https://hebrewbooks.org/pdfpager.aspx?req=60389&st=&pgnum=55
Why would צורת הפתח be acceptable for כלאים but not for Shabbos?
Learn תוס’ “אילימא