A short is substituted for pū etc. before a śit affix.,
The Pvadi roots form a subdivision of the Kryadi class, beginning with पूञ् पवने (2) and ending with प्ली गतौ (32). The ल्वादि roots 8.2.44 are a portion of प्वादि (numbers 13 to 32). Others hold that upto the end of the Kryadi class are Pvadi. Thus पुनाति, लुणाति, स्तृणाति ॥ Those who hold that Pvadi roots are upto the end of the Class, explain the non-shortening of जानाति (for ज्ञा would also then become Pvadi), by saying that the express text of 7.3.79, substituting long जा prevents the shortening. They say had ज्ञा been also shortened, then merely ज substitute would have been enough and not जा; and this ज would have been lengthened in the case of जन् by 7.3.101, to form जायते ॥,
