Is Standing During the Pledge of Allegiance Required in California?

Alright, I've found myself a quandary. I've got someone who insists that California's policy as well as our local school district's policy is that, even if the Pledge isn't said, students must stand while it is being recited. So far, I've yet to find any source that states it is currently disallowed, as well as some court cases fighting similar laws in other states, but nothing pertaining to California itself. I need clear, written, legal proof that this can not be required in the state, or otherwise, someone can correct me if I'm wrong and it is required. So far, Google hasn't helped, and neither has the ACLU website. Does anybody have a good source on this?