Reference for Eruvin 177:3
<br><br><big><strong>הדרן עלך כיצד משתתפין</strong></big><br><br>
A SINGLE DOMAIN,<span class="x" onmousemove="('comment',' And it is permitted to carry objects from one roof into another on the Sabbath.');"><sup>7</sup></span> PROVIDED NO ROOF IS TEN HANDBREADTHS HIGHER OR LOWER THAN THE NEIGHBOURING ROOF;<span class="x" onmousemove="('comment',' Cf. MS.M. The last four words are wanting from cur. edd. If one roof was higher or lower than the one adjoining it no objects may be moved on the Sabbath from the one into the other.');"><sup>8</sup></span> SO R'MEIR'THE SAGES, HOWEVER, RULED: EACH ONE IS A SEPARATE DOMAIN.<span class="x" onmousemove="('comment',' Lit., 'before itself', so that where the tenants did not join in one 'erub the movement of objects from one roof to the other is forbidden.');"><sup>9</sup></span>