Script grammar is a grammar at the level of scripts. It is a unique characteristic of Indian languages. Unlike western languages, Indian scripts are directly based on phonetics. The units of orthography are essentially C*V syllables where C denotes consonant sound and V denotes vowel sound. C*V syllables are known as aksharas, the atomic units of writing. There are more than 5000 aksharas covering the words of all the major Indian languages. Script Grammars define the manner in which a script of a given (Indian) language is to be written.
The script grammar is a grammar of scripts. It accepts only valid aksharas. This is to ensure that invalid sequences do not occur in any language.