Siman - Shabbos Daf 7

• Karmelis - Nook adjacent to reshus harabim

R’ Yochanan identifies the karmelis listed as one of the karmelis areas as a nook adjacent to a reshus harabim. Although the public sometimes pushes their way into this area and enter it, since it is not convenient it is a karmelis.

• Lenient parameters of a karmelis

The Rabbis were lenient when decreeing the parameters of a karmelis, applying one of the leniencies of a reshus hayachid and one of the leniencies of a reshus harabim.  

- Rav Dimi said in the name of R’ Yochanan that a karmelis must be at least four tefachim wide, similar to the requirement for a reshus hayachid. If it less than four tefachim it has the status of a makom petur.

- Rav Sheishess said the airspace of karmelis is only considered a karmelis until ten tefachim, similar to the laws of a reshus harabim. The area above a reshus harabim has the status of a makom petur.

• Crevices (חורים)

Crevices in a reshus hayachid  (חורי רשות היחיד) have the status of reshus hayachid.

Crevices in a reshus harabim (חורי רשות הרבים) :

- Abaye says they are treated as a reshus harabim since the public sometimes uses them as a convenient place to store items.

-Rava says their measurement determines their status. If they are less than four tefachim wide they have the status of a makom petur. If they are four tefachim or wider then they are treated as a karmelis.