Section 2. Survey Instruments/Equipment. The following instruments/equipment may be used in the conduct of surveys of ancestral domains/lands: transit, theodolite, total station, steel tape, electronic distance measurement instrument (EDM), or GPS. To ascertain that these instruments are fit for use and capable of achieving the prescribed survey accuracy for registration purposes and conform to the survey standards provided under Sec. 15 to 37, Chapter II of DAO 98-12, a certification to that effect shall be issued by the Lands Management Bureau (LMB) or NAMRIA. When GPS is to be used in the survey, the authorized/accredited geodetic engineer must submit to ADO the following information for purposes of determining whether it conforms to the survey standards provided under Sec. 58, Chapter III of DAO 98-12: a. b. c. d. e. f. Type of GPS receivers (brand/model) Survey technique/method Elevation mask Antenna setup specifications and/or antenna type Number of receivers Certification of Calibration and Registration of the instrument issued by NAMRIA Section 3. Level and Standard of Accuracy. Surveys that will require the use of relative positioning technique shall follow the provisions provided under Section 47 to 57, Chapter III, Part I of DAO 98-12. For geodetic and project control surveys where conventional survey instruments will be used, Section 112 to 116, Chapter IV, Part I of DAO 98-12 shall apply. Section 4. Survey Rules in the AD/AL Delineation. In locating corners for purposes of delineating ancestral domains/lands the following rules and techniques shall be observed: a. Where the AL/AD area being surveyed adjoins other ALs/ADs with issued CADT/CALT, the corners or boundaries of the latter shall be adopted as boundary of the former. b. When natural features like bodies of water define the boundaries of an ancestral land/domain, the first and last corners situated along natural features shall be marked with monuments prescribed in Part II, Rule IV, Section 1, items a-c. Intermediate corners along the natural features may be marked with monuments described in Part II, Rule IV, Section 1, items b-d. c. In cases where bodies of water serve as the boundary between adjoining AL/AD claim/s and its claimants opted to use the inaccessible location of the same as their boundary, at least two (2) witness monuments shall be established on the ground following Part II, Rule IV, Section 1, item e hereof. d. When peaks and ridges constitute the boundary of the AL/AD, the corners shall be placed at appropriate distances following the general curves of the natural features. e. The distance between succeeding corner monuments should not exceed 500 meters for AL. f. For AD, a 1,000 meter-distance between succeeding corner monuments, preferably intervisible, shall be observed. In excess of 1,000 meters, a written justification shall be submitted putting in detail the cause and effect of such undertaking. g. Where the AD covers coastal areas, the portion of the AD constituting the land area shall be surveyed/delimited separate from the water area and the respective technical descriptions shall be described in the survey plan. The corners defining the boundary between the land and water portion of the AD may be used as witness monuments to the submerged/inaccessible corners. RULE IV CORNER MARKERS OF ANCESTRAL LANDS/DOMAINS Section 1. Types of Monuments or Markers. The position of points and corners of ancestral land/domain shall be defined and marked on the ground by monuments or markers of permanent nature, except when corners lie near physiographic or natural features. The mixture for concrete monuments consists of one (1) part cement, two (2) parts sand, and four (4) parts gravel or broken stone. Page 22 of 26 Revised Omnibus Rules on Delineation and Recognition of Ancestral Domains and Lands of 2012