The Tai Tham script (Northern Thai: ᨲ᩠ᩅᩫᨾᩮᩬᩥᨦ, Dai Tam; Tai Lü: ᦒᧄ , Tham, "scripture"), also known as the Lanna script or Tua Mueang, is used for three living languages: Northern Thai (that is, Kham Mueang), Tai Lü and Khün. In addition, the Lanna script is used for Lao Tham (or old Lao) and other dialect variants in Buddhist palm leaves and notebooks. The script is also known as Tham or Yuan script.
The Northern Thai language is a close relative of Thai and member of the Chiang Saeng language family. It is spoken by nearly 6,000,000 people in Northern Thailand and several thousand in Laos of whom few are literate in Lanna script. The script is still read by older monks. Northern Thai has six linguistic tones and Thai only five, making transcription into the Thai alphabet problematic. There is some resurgent interest in the script among younger people, but an added complication is that the modern spoken form, called Kammuang, differs in pronunciation from the older form.
There are 670,000 speakers of Tai Lü of whom those born before 1950 are literate in Lanna script. The script has also continued to be taught in the monasteries. There are 120,000 speakers of Khün for which Lanna is the only script.
There are currently a few fonts that support this range. Thai people are used to typing the Thai script by placing a front vowel before a consonant; this might cause incorrect input method for Tai Tham script because the consonant must be always typed before the associated vowel, regardless of the relative written position of the vowel, similar to typing the Khmer, Myanmar or Tamil script.
^Natnapang Burutphakdee (October 2004). Khon Muang Neu Kap Phasa Muang [Attitudes of Northern Thai Youth towards Kammuang and the Lanna Script] (PDF) (M.A. Thesis). Presented at 4th National Symposium on Graduate Research, Chiang Mai, Thailand, August 10-11, 2004. Asst. Prof. Dr. Kirk R. Person, adviser. Chiang Mai: Payap University. P. 7, digital image 30. Archived from the original on 2013-06-14. Retrieved June 8, 2013. "The reason why they called this language ‘Kammuang’ is because they used this language in the towns where they lived together, which were surrounded by mountainous areas where there were many hill tribe people."
ISO/IEC 10646:2003/Amd.5:2008 Universal Multiple-Octet Coded Character Set (UCS) -- Amendment 5: AMENDMENT 5: Tai Tham, Tai Viet, Avestan, Egyptian Hieroglyphs, CJK Unified Ideographs Extension C, and other characters