Extended Tamil script

Extended-Tamil script or Tamil-Grantha refers to a script used to write the Tamil language before the 20th century Tamil purist movement.^[1] Tamil-Grantha is a mixed-script: a combination of the conservative-Tamil script that independently evolved from pre-Pallava script, combined with consonants imported from a later-stage evolved Grantha script (from Pallava-Grantha) to write non-Tamil consonants.^[2] Some scholars posit that the origin of Tamil-Grantha is unclear: the script could also be a direct descendant of the Pallava-Grantha script which extensively developed during the Middle Tamil period to write Middle-Tamil.^[3]

The Modern Tamil script is a subset of Tamil-Grantha alphabet, retaining only the 18 consonants taken from Tolkāppiyam-based Old Tamil which generally was written using Vatteluttu script. Tamil-Grantha has 36 consonants, hence covering all Indic consonants like Malayalam script.^[4] However, the Modern-Tamil standard allowed a few additional consonants from Grantha into its alphabet: ஜ (ja), ஷ (ṣa), ஸ (sa), ஹ (ha). But their usage is discouraged by Tamil purists and recommend^{[clarification needed]} to assimilate the sounds to approximate pure-Tamil phonology, respectively: ச (ca), ச (ca), ச (ca), க (ka). Another letter ஶ was also allowed in 2005^[5] exclusively to write ஶ்ரீ (śrī); however purists enforce the usage of திரு (tiru) over ஶ்ரீ.

In terms of utility, the major difference between Modern-Tamil and Tamil-Grantha is that the former is a phonemic script (where voiced consonants are treated as allophones of the voiceless consonants, and no aspirated consonants), and the latter is a fully-phonetic script. Hence, if one were to write only pure-Tamil-derived words in their text, it is enough (and minimally efficient) to use the Modern-Tamil script. However if one were to include non-South-Dravidian words in their text, using the pure-Tamil script can cause errors in pronunciations since the phonemic-transcription rules of Tamil Grammar does not apply to such vocabularies. So depending on the domain of text (and number of loan words), writers used either the minimal-Tamil script or extended-Tamil script. To write or transliterate Sanskrit texts, the full Grantha script was used instead of Tamil-Grantha.