The final vowel of śara etc. is lengthened before mat when it is a name.,
As शरावती, वंशावती ॥ The म of मत् is changed to व because it is a Name 8.2.11. But not so after व्रीहि &c as these belong to यवादि class 8.2.9.
1 शर, 2 वंश, 3 धूम, 4 अहि, 5 कपि 6 मणि, 7 मुनि, 8 शुचि, 9 हनु.,