Wikipedia
Vaikhānasa is one of the principal traditions of Hinduism and primarily worships Vishnu (and his associated Avatars) as the Supreme God. The followers are mainly Brahmins of Krishna Yajurveda Taittiriya Shakha and Vaikhanasa Kalpasutra. The name Vaikhānasa stands for the followers and the fundamental philosophy itself with the name derived from founder, Sage Vaikhanasa. It is principally monotheistic in its philosophy, whilst also incorporating elements which could be described as being panentheistic. Vaikhanansas principle focuses on rituals and worship of Lord Vishnu rather than the philosophy of Uttara Mimamsa, unlike Vaishnavism, the larger and more prevalent form on Vishnu worship.
Vaikhanasa bhagavath Shastra is the guiding principle for rituals in Tirumala Venkateswara temple.