Most of the provinces are further subdivided into numbered districts.There are also some sub-provinces, which generally split off and form separate provinces in due course. The municipalities are similar in size to the chartered cities, but generally lower in population.Edward Jassen dela Pea sent me a pdf file containing the data for the 2007 Philippine census. There are also some minor spelling changes, and the code for one of the old regions is changed.
Note 1: I reported in "Administrative Subdivisions of Countries" that the capital of Maguindanao moved from Maganoy to Sultan Kudarat in ~1978.
Note 2: This is the code for Manila, considered as a chartered city, that was given in the draft standard ISO/DIS 3166-2 (1996).
ISO 3166-2 has not had a code on this level for the Metropolitan Manila region since the official standard came out in 1998. The first two digits represent a province, district, or city. The Philippines have been divided into provinces since they were a Spanish colony, although there have been many changes in the division.
David Short informed me of the creation of the Negros Island Region. The capital of the new region has not yet been chosen; Bacolod City is the largest city in the region. On 2015-11-27, ISO issued the code , but that's for the "highly urbanized city" Manila; it's not clear whether that is equivalent to the region of Metropolitan Manila, which is the same as National Capital Region.
It used the same codes as ISO for all the provinces, except for Davao Occidental, which was new at the time.