Tibetan is a Unicode block containing characters for the Tibetan, Dzongkha, and other languages of China, Bhutan, Nepal, Mongolia, northern India, eastern Pakistan and Russia.
The Tibetan Unicode block is unique for having been allocated in version 1.0.0 with a virama-based encoding that was unable to distinguish visible srog med and conjunct consonant correctly.
[note 1] This encoding was removed from the Unicode Standard in version 1.0.1 in the process of unifying with ISO 10646 for version 1.1,[3] then reintroduced as an explicit root/subjoined encoding, with a larger block size, in version 2.0.
Moving or removing existing characters has been prohibited by the Unicode Stability Policy for all versions following Unicode 2.0, so the Tibetan characters encoded in Unicode 2.0 and all subsequent versions are immutable.
[4] The following Unicode-related documents record the purpose and process of defining specific characters in the Tibetan block: