老傣文

Tai Tham is a Unicode block containing characters of the Lanna script used for writing the Northern Thai (Kam Mu'ang), Tai Lü, and Khün languages.

The Tai Tham script (Northern Thai pronunciation: , tua mueanɡ; 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.