sa is substituted for samān before brahmacārin when it denotes persons engaged in fulfilling a common vow of studying the Vedas.,
Thus समानो ब्रह्मचारी = सब्रह्मचारी ॥ ब्रह्म means the Vedas. The vow of studying the Veda, is also called ब्रह्म ॥ He who is engaged in the performance of that vow is called ब्रह्मचारिन् ॥ समान refers to the vow, the vow of studying being common to both : i. e. समाने ब्रह्मणि व्रतचारी = सब्रह्मचारी ॥ According to Bhattoji Dikshit चरणे in the sutra means a शाखा or a department of Vedic study. He who has a common (samana) branch (charana) is a sabrahmchari.,