The purpose of re-establishment of Old Schedule Lots is to identify on ground and to re-survey the surviving boundary features (original occupation) as depicted on the DD Sheets, or to construe the lot boundaries based on the surviving ground features as recorded on the DD Sheets.
Old Schedule Lots are those land parcels in the New Territories held under the Block Government Lease granted in 1905. The Block Government Lease consists of the Indenture, the Schedule of Government Leases and the DD Sheets at a scale of 1:3960 or 1:1980. The Block Government Lease constitutes the primary evidence of title to land in the New Territories.
What the Law Says
In Wu Muk Fung v Vocalion Estates Ltd  High Court Action No. 902/1986 in the Supreme Court of Hong Kong, the Court accepted that the boundaries of the Old Schedule Lot could not be re-established better than 3 metres by relying on the DD Sheet.
In Lam Pak Kau v Yu Yuet Fat  CACV 205/99 in the High Court of the Hong Kong Special Administrative Region, the Court accepted that it was not possible, using the tools available, to place a boundary of an Old Schedule Lot with more accuracy than within about 1 metre.
In Secretary for Justice v Wing Lung Wai Community  CACV 173/1996 in the Supreme Court of Hong Kong, the Court of Appeal held that the most important thing was to ascertain what was intended to be granted under the Block Government Lease. If it was impossible to extract the parties’ intention with any sort of clarity from the four corners of the Block Government Lease, the Court had to look at all the surrounding circumstances.
In Lintock v Attorney General  HC Action No. 5820/1982 of Supreme Court of Hong Kong, the Court held that as it was impossible to extract the parties’ intention with any sort of clarity from the four corners of the Block Government Lease, the Court had got to go outside it. The Court had to look at all the surrounding circumstances, but it was a process of construction, not rectification of the Block Government Lease.
In Harvest Rise Development Limited v Ling Yau Yung  HCMP No. 109/2002 in the High Court of the Hong Kong Special Administrative Region, the Court held that although the assignments expressly provide the property assigned was as “more particularly delineated and described” on the annexed plan, this was not to say that the Court was then bound to follow the plan where the Court had ascertained what the parties intended to be assigned.
In Wilson v Greene  ER 1098, where, prior to the contract for sale of land, the boundary was marked out on the land itself and agreed to by the parties, the Court might have regard to this as the “surrounding circumstances” construing vague parcels in the subsequent conveyance.
Discussion and Conclusion
For the Old Schedule Lots, the indenture of Block Government Lease states that the piece of land described in the schedule is more particularly delineated and described on the DD Sheet attached to the Block Government Lease. The DD Sheets were drawn in relatively small scale and the land parcels marked therein bore no absolute positional relationship to a survey system, thus the DD Sheets contain ambiguity in the boundary definition.
To re-establishment the land boundaries, therefore, it is necessary to ascertain what was intended to be granted and to construe the Block Government Lease as a whole by looking at all the surrounding circumstances.
The DD Sheets actually were to depict the actual occupation features for owners to claim their land holdings between 1898 and 1903. The re-establishment of land boundaries of Old Schedule Lots is therefore to survey the original features which formed as boundaries delineated in the DD Sheet at the time when it was drawn up. It is a process of construction, not rectification of the Block Government Lease.