After the name of a Vedic School, the affixes which denote the rule of that school, also come in the sense of 'collection thereof'.,
The Vedic Schools or Charanas are like कठ, कलाप &c. The affixes denoting the rule of the School are those taught in Sutra 4.3.126 &c. The word धर्म does not occur in the Sutra 4.3.126, or any where else, but it occurs in the following ishti under that Sutra:-चरणद्धर्माम्नाययोः ॥ Thus कठानां धर्म = काठकम्, so also कठानां समूहः = काठकम् ॥ Similarly कालापकम्, छान्दोग्यम्, औक्धिक्यम् and आथर्वणम् ॥,