Muban geocodes

The geocodes for provinces, district and subdistricts include another two digits at the end for the villages (muban, หมู่บ้าน). The villages itself had a numerical code long before that geocode system was introduced, they are named หมู่ที่ # (Mu Ti #). While they also have a name, this does not have to be unique - the term "village" is a bit misleading, larger settlements may be subdivided into several muban sharing the same name but obviously different numbers. On the other hand there are also muban which cover several small settlements and thus have two or three names. Hence the name is not a possible way to identify a muban, but the number is the only unambiguous way.

So for example Bang Boet Lang (บางเบิดล่าง or village 1 of subdistrict Bang Bai Mai in Mueang Surat Thani district has the geocode 84010501 - province code 84, Mueang district always have the 01, and the subdistrict has the number 5. A case where the name is not unique are villages 1 to 4 of Phai Khwang subdistrict, Mueang Phichit district, which are all named Ban Dan (บ้านดาน); finally village 8 of Samo Khae subdistrict in Mueang Phitsanulok is named Ban Chat Kaeo - Chin Lap (บ้านฉัตรแก้ว-ชินลาภ), a name listing the two settlements which are comprised into this single administrative entitiy.

There is however a problem with the village numbers as well - they are not stable in time. At least till the end of the 1990s, when the last subdistricts were created - the villages left after splitting off a new subdistrict get renumbered, so a given code can refer to two different villages, one always have to add the date one is using. The codes for the higher levels however do not get reused, so it has districts and provinces where the numbers of the sub-entities have holes. However only a few of the Royal Gazette announcements on the subdistrict creations explicitly state the renumbering, like the one of Sala Lai (ตำบลศาลาลัย), Sam Roi Yot, Prachuap Khiri Khan in 1995, in most cases this was done implicitly.

To make this even more confusing - there are subdistricts where the village numbers has hole. The first one I came across is probably a mistake. In the 2008 announcement with tambon area clarification of Lum Din (ตำบลหลุมดิน), Amphoe Mueang Ratchaburi number 1 is missing, however in the similar announcement from 1998 the same list of names starts with one instead. But Wat Chan (ตำบลวัดจันทร์) subdistrict of Mueang Phitsanulok really only has villages 2, 4, 7 till 10, as one can see in a 2006 Gazette announcement as well as the website of the TAO. But I cannot find yet what had happened with the villages having the missing numbers, there was no new subdistrict created there recently, maybe they have been reassigned to the city of Phitsanulok and thus subdistrict Nai Mueang?