Romanization of Thai Script
Thai script will be transcribed following the Royal Thai General System of Transcription, which is the only generally accepted rule for transcription. Unfortunately, this System is not widely adopted, and if adopted then often not consistently. Therefore, spelling or transcription variants are frequently published, which do not base on a rule other then individual, native-language adaptation of pronunciation of Thai words, and can only lead to confusion.
An example of a widely used transcription variant is the Thai word for bamboo (ไผ่), which is correctly transcribed "phai", and not "pai". The digraph "ph" in words transcribed from Thai indicates an aspirated "p" (and represents the sound of "p" like the name Paul), whereas the digraph "ph" in English words usually derives from Greek φ (and represents the sound of "f" like photograph).
For all Thai geographical names, Thai plant names, and other words in Thai script, the Royal Thai General System of Transcription will be strictly adopted. For Thai personal names, the same System applies, except if it is known that a certain person uses his or her own constant way of Romanization, then this will be followed.
The International Organization for Standardization (ISO) offers transliteration rules of Thai script (ISO 11940), published 1998 and updated 2003, which is virtually not in use except by linguists.