Royal Thai General System of Transcription

The Royal Thai General System of Transcription (RTGS) is the official system for rendering Thai in the Latin alphabet. It is used in road signs and government publications, and is the closest thing to a standard of transcription for Thai, though its use by even the government is inconsistent.

Features

Prominent features of the Royal Thai General System include (IPA is the International Phonetic Alphabet):
* uses only straight letters from the latin alphabet, no diacritics
* spells all vowels and diphthongs using only vowel letters: a, e, i, o, u
** simple letters (a, e, i, o, u) are simple vowels (same value as in IPA)
** combinations with "e" (ae, oe, ue) are simple vowels (first two values close to similar ligatures in IPA)
** combinations with "a", "i", "o" (or several) are diphthongs (indicated by a, j and w respectively in IPA)
* uses consonants as in IPA, except:
** combinations with "h" are used for aspirated k, p, t (similar to letter with superscript h in IPA), to distinguish them from the separate unaspirated k, p, t
** uses "ng" for IPA
** uses "ch" for IPA and
** uses "y" for IPA
** note that transcription of consonants in final position is according to pronunciation, not spelling

Criticism

The Royal Thai General System has been criticized as inadequate for learners of Thai, particularly because of the following shortcomings:
* it does not record tones
* it does not differentiate between short and long vowels
* notation "ch" does not differentiate between IPA and IPA (see table below)
* notation "o" does not differentiate between IPA and IPA (see table below)

	Letter 1				Letter 2
RTGS	Thai	IPA	Description	English	Thai	IPA	Description	English
ch	จ		alveo-palatal affricate	as "ty" in "let you"	ฉ, ช, ฌ		aspirated alveo- palatal affricate	as "ch" in "check"
o	โ�"ะ, �"		close-mid back short rounded	like "oa" in "boat"	เ�"าะ		open-mid back short rounded	like "aw" in "raw", but shorter
	โ�"		close-mid back long rounded	like "oa" in "moan"	อ�"		open-mid back long rounded	like "aw" in "raw"

Transcription table

For consonants, the transciption is different depending on the location in the syllable. In the section on vowels a dash ("–") indicates the relative position of the initial consonant belonging to the vowel.
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	Vowels

	Final position
ก	k	k
ข	kh	k
ฃ	kh	k
ค	kh	k
ฅ	kh	k
ฆ	kh	k
ง	ng	ng
จ	ch	t
ฉ	ch	t
ช	ch	t
ซ	s	t
ฌ	ch	t
ญ	y	n
ฎ	d	t
ฏ	t	t
ฐ	th	t
ฑ	d	t
�'	th	t
�"	n	n
�"	d	t
ต	t	t
ถ	th	t
ท	th	t
ธ	th	t
น	n	n
บ	b	p
ป	p	p
ผ	ph	p
ฝ	f	p
พ	ph	p
ฟ	f	p
ภ	ph	p
ม	m	m
ย	y	-
ร	r	n
ฤ	rue, ri, roe	-
ฤๅ	rue	-
ล	l	n
ฦ	lue	-
ฦๅ	lue	-
ว	w	-
ศ	s	t
ษ	s	t
ส	s	t
ห	h	-
ฬ	l	n
ฮ	h	-