 Its absence signifies perfective aspect, and it may be further suffixed with "-yan", producing "-ma-yan", to denote continuous or imperfective aspect.The "-ma" suffix exhibits regular allomorphy; it assimilates in place and manner of articulation to any preceding obstruent or nasal, but not to any preceding lateral, rhotic or approximant.That is, it remains "-ma" following vowels, or following the consonants [r], [l], [w] and [j], but when it follows [p], for instance, it assimilates in manner and place, and becomes /-pa/, as in "dup-pa" 'sit'.