122.—(1) This rule applies where—
(a)there is—
(i)a transfer of part of a registered estate in land, or
(ii)the grant of a term of years absolute which is a registrable disposition of part of a registered estate in land,
(b)there is a common boundary, and
(c)there is sufficient information in the disposition to enable the registrar to determine the exact line of the common boundary.
(2) The registrar may determine the exact line of the common boundary and if he does he must—
(a)make an entry in the individual registers of the affected registered titles stating that the exact line of the common boundary is determined under section 60 of the Act, and
(b)subject to paragraph (3), add to the title plan of the disponor’s affected registered title (whether or not the disponor is still the proprietor of that title, or still entitled to be registered as proprietor of that title) and to the title plan of the registered title under which the disposition is being registered, such particulars of the exact line of the common boundary as he considers appropriate.
(3) Instead of, or as well as, adding particulars of the exact line of the common boundary to the title plans mentioned in paragraph (2)(b), the registrar may make an entry in the individual registers of the affected registered titles referring to the description of the common boundary in the disposition.
(4) In this rule—
“common boundary” means any boundary of the land disposed of by a disposition which adjoins land in which the disponor at the date of the disposition had a registered estate in land or of which such disponor was entitled to be registered as proprietor, and
“disposition” means a transfer or grant mentioned in paragraph (1)(a).