My puzzlement about the Thai language, especially its transliteration into western script grows. "There are 44 consonants classified into 3 categories depending on the kinds of vowels they are associated with. Vowels are indicated by symbols, or combinations of symbols, that may appear before, after, or even around the consonant. The Thai government has instituted the Royal Thai General Transcription System (or RTGS) as a standard method of writing Thai using a Roman 26-letter alphabet." ('Lonely Planet Phrasebooks: Thai', 2004)
Nevertheless, the level of standardization seems to be far from universal. You routinely see the same word spelled different ways in transliteration. Also, my Thai friends tell me that even in Thai, the same word is spelled differently by different people in different situations.
You may also look at this web site for more information.
As you might imagine, this impedes libraries from easily sharing cataloging data and other information in some cases.
Lots to learn here.