Traditional Mongolian script, which is a cursive script in which the actual written form of a character depends on its context (including its position in a word and the preceding character, with which it may form a ligature), has recently been the subject of international standardisation within the scope of ISO/IEC 10646 and Unicode. In most cases the context determines the particular "variant form" of each character uniquely, and the encoding scheme adopted has made use of this fact by encoding only a single variant form of each character, together with control characters which can be used both to select between alternative possibilities in cases where more than one variant form is possible and to override a unique default form when non-standard text is required. This of course means that the character set encoding is both simpler and smaller, but unfortunately introduces complications when it comes to implementing software systems supporting the traditional Mongolian script.

This paper gives an overview of the encoding and the principles on which it is based and explains how the variant forms of characters and the ligatures are obtained from it. In addition, issues relating to the implementation of software systems for traditional Mongolian script are discussed.