altering user tag input I have a content type that allows users to make their own tags, for me to be able to properly search through these tags I need them to be in a specific format.

Rather than burden users with my strict formatting guideline I would like to just alter the input to my format before creating the tag. Is such a thing possible?
Implement  hook_taxonomy_term_presave  in a custom module and alter the terms according using PHP's string manipulation functions.