Brunei–Malaysia border which are defined by agreements, from west to east, are as follows: Brunei and Malaysia in an Exchange of Letters on 16 March 2009, agreed to affirm the five agreements. The two countries also agreed to use the watershed principle to determine the remaining undelimited portions of the border. Brunei's maritime boundary with Malaysia until the 100 fathom isobath was inherited from the Sarawak (Definition of Boundaries) Order in Council 1958 No 1518 and the North Borneo (Definition of Boundaries) Order in Council 1958 No 1517, both of which defined the boundary between Brunei on the one hand, and Sarawak
Indonesia–Malaysia border between the two countries for this segment of their maritime border. The border follows the equidistant line between the baselines of Indonesia and Malaysia and Point 20 is the equidistant point between Indonesia, Malaysia and Vietnam (see table below). Point 20 is the western terminus of the Indonesia-Vietnam continental shelf boundary which the two countries agreed to in 2003 and the easternmost point of the area of overlapping claims between Malaysia and Vietnam. The southern termninus of the continental shelf boundary lies to the east of Pedra Branca which was disputed between Malaysia and Singapore and eventually awarded to Singapore