(written from a Production point of view)
Referenced in the first draft script of the Star Trek: Enterprise first season episode "Fusion" (which had the working title "Equilibrium"), the Festival of T'Plana Hath was a holiday observed on the planet Vulcan. The celebration, in common with the Vulcan holiday of Kal Rekk, was observed by "sitting in silence and meditating." In the aforementioned teleplay, Fraht told Trip Tucker about the Festival of T'Plana Hath. It was presumably named after the revered Vulcan matron T'Plana-Hath.