The twolc file is written in the Koskenniemi-style twolc format. The rule set is still preliminary. The alphabets, sets and rules are documented in * [the generated version of the documentation|smn-phon-phonology.html] found in the twolc file itself. Here we discuss the linguistic principles to be modeled from a more general perspective. !!!Stem vowel alternation tbw. !!!Consonant gradation tbw. !!!Consonant lengthening tbw. !!!Vowel changes tbw.