כל מחיצה שלא נעשית לדור בתוכה אלא לצניעות או לשמור מה שיתנו בתוכה או לישב בה כדי לשמור השדות היא מחיצה לטלטל מה שבתוכה אבל אינה מחיצה לעשות מה שבתוכה מוקף לדירה אם הוא יותר מב' סאתים הילכך אילן שענפיו יורדין למטה אם אינם גבוהים שלשה מן הארץ ועיקרן במקום שמחוברים לאילן הוא גבוה עשרה חשיב מחיצה ומותר לטלטל בכולו והוא שימלא האויר שבין הענפים בעצים או בקש ויקשור הענפים שלא ינידם הרוח שכל מחיצה שאינה יכולה לעמוד ברוח מצויה אינה מחיצה ודוקא עד בית סאתים אבל יותר מבית סאתים לא אפי' נטעו לכך כיון שאינו עשוי לדור בתוכו אלא להסתופף בצלו לשמור השדות:

Any partition that was not made to dwell inside it, but rather for privacy, or to guard what is placed inside it, or to sit in it in order to guard fields — it is a valid partition for carrying within it, but it does not make what is inside it an enclosed dwelling (mukaf l'dirah) if it is more than two se'ah. Therefore, a tree whose branches hang down — if they are not three handbreadths above the ground, and their base where they connect to the tree is ten handbreadths high — it is considered a partition and one may carry throughout it, provided one fills the airspace between the branches with wood or straw and ties the branches so the wind does not move them, for any partition that cannot withstand an ordinary wind is not a valid partition. This applies only up to two se'ah, but more than two se'ah is not valid, even if the tree was planted for this purpose, since it is not made to dwell inside but to sit in its shade to guard the fields.

A mound that is five handbreadths high, and one completed it to ten by making a partition five handbreadths high on top of it — it is considered a valid partition for carrying and for all purposes.

A partition that stands on its own — meaning one not made for the purpose of being a partition — is valid. A partition made on Shabbat is valid, and this applies when it was made unintentionally (shogeg), but if done intentionally (meizid) it is a partition only to be stringent — to make one liable for throwing from a public domain into it — but not to permit carrying within it. This applies when there was no partition there previously; but if there was one, it was removed, and then re-formed, even intentionally, it reverts to its original permitted status. For example, two or three people who surrounded themselves with mats in a public domain and also divided between themselves with mats and made an eruv together — they are permitted to carry from one area to the other. If the mats were rolled up, it became forbidden; if they were spread out again, even intentionally, they revert to their original permitted status.

One may carry throughout a boat, even if it is more than two se'ah, since it is considered enclosed for dwelling (see above Siman 366 and end of Siman 382). If it was turned upside down to dwell beneath it, it constitutes a private domain (reshut hayachid) even on top of it. If it was turned upside down to caulk it (l'zofta), one may only carry within four cubits if it is larger than two se'ah.

One may make a partition with any material — with vessels, with saddles — whether using only horizontal elements (erev) such as ropes, or only vertical elements (shti) such as reeds stuck in the ground. These are permitted up to two se'ah, even for an individual in a settled area, provided there is not a gap of three handbreadths between one rope and another or between one reed and another. This applies even with animals, provided they are tied; and even with people standing next to each other less than three handbreadths apart — even when walking they are considered a partition and the space between them is a private domain — provided they do not know they were positioned to serve as a partition. If even one of them knows, it is forbidden. And even if one did not inform them that he is now making partitions, if it is likely they would find out — such as if he once already made a partition from them — he may not do so again.

If they came initially without knowledge, even if they later became aware, there is no concern.

Some say that the person who wishes to use this partition should not position the people himself, but rather another person should position them without their knowledge. Rema: One should only make a partition of people in a time of need and pressing circumstance. If one forgot something in a public domain, it is preferable to send children to bring the object without a partition than to make a partition of people and have an adult bring it. (Beit Yosef in the name of Shibolei HaLeket, Semag, and Sefer HaIttur)

If the open space exceeds the standing space, it is forbidden, unless each individual gap is less than three handbreadths.

If the open space equals the standing space, it is permitted, whether in vertical or horizontal elements, provided no single opening is more than ten cubits. Up to ten cubits is permitted because it is like a doorway.

If one made a tzurat hapetach, even for a breach wider than ten cubits it is permitted, even if one only planted four posts in four directions and made a tzurat hapetach over them. This applies in a courtyard or alleyway that has residents; but in an open field it does not help in all directions through a tzurat hapetach. According to the Rambam, a tzurat hapetach does not help for a breach wider than ten cubits unless the standing space exceeds the open space. (In that case it helps even in an open field in all directions.) (Beit Yosef in the name of Semag and Semak)

What constitutes a tzurat hapetach? A reed on this side and a reed on that side, and a reed on top of them — even if the top reed does not touch them but there are several cubits between them — provided the side reeds are ten handbreadths high and are aligned directly below the upper reed. If one attached the upper reed to both side reeds or to one of them from the side, it is not valid. The side reeds must be sturdy enough to hold even the smallest door, even one of straw or reeds; but the reed on top need only be any size at all, and even a rush (gemi) is valid.

An arch (meaning a gate made in an arch shape. Rashi) if its legs, meaning before it begins to curve, are ten handbreadths high, it is permitted as a tzurat hapetach.