מבוי המפולש בשני ראשיו לרה"ר או צד א' לרה"ר וצדו השני לכרמלית הגה או שני ראשיו פתוחין לכרמלית (ריב"ש סימן ת"ה) צריך צורת הפתח מכאן ולחי או קורה מכאן אבל אם צדו א' פתוח לרה"ר וצדו השני לחצר שאינה מעורבת אין צריך אלא לחי או קורה בשני ראשיו: הגה וכל זה יש לו תנאים המבוארים לעיל סי' שס"ג סכ"ז בדין מבוי אבל אם אינו רק בחצר צריך תיקון חצר משני צדדיו:

Laws of a Pass-Through Alleyway and One Shaped Like the Letter Nun — 5 Sections A pass-through alleyway open at both ends to a public domain, or with one side opening to a public domain and the other to a karmelit— or with both ends opening to a karmelit requires a doorframe shape on one side and a lechi or beam on the other. But if one side opens to a public domain and the other to an uneruvated courtyard, only a lechi or beam is needed at each of the two ends.All of this is subject to the conditions explained above in Siman 363, section 27, regarding the laws of an alleyway. But if it is entirely within a courtyard, it requires the courtyard arrangement on both sides.

A public domain itself can only be rectified with doors, and they must be locked at night. Some say that even if they are not locked, they must at least be fit to be locked — so if they are sunken in the ground, one clears them and fixes them so they are fit to be locked. Once the door arrangement is made, the entire area is considered a single courtyard and its alleyways require no further arrangement.

A bent alleyway shaped like the letter dalet is treated as if it were a pass-through alleyway at the bend, and requires a doorframe shape at the bend. At each of its two ends it needs either a lechi, beam, or doorframe shape — and a lechi or beam at the bend. If it is shaped like the letter chet, it requires a doorframe shape at each of its two bends, and a lechi or beam at each of its two ends.

Alleyways that open into one another — when the bend of one of them does not face the public domain — since the outer alleyway opens to the public domain, the alleyway that opens into it at its bend is considered as if it opens to the public domain. And so too the alleyway that opens into that one, and so on for all of them.

An alleyway shaped like the letter nun meaning a large alleyway into which many small alleyways open, with the other ends of the small ones opening to the public domain — even if the openings of the small alleyways on each side do not directly face one another: one makes a doorframe shape for each small alleyway at the point where it opens into the large alleyway, and a lechi or beam at its other end which opens to the public domain. As for the large alleyway itself: if it is a pass-through, one makes a doorframe shape on one side and a lechi or beam on the other; if it is closed at one end, one makes a lechi or beam at its open end.