"Don't ask, don't tell" was a law set by former President Clinton in 1994 that prohibited discrimination against gay and bisexual military service members that were closeted. The purpose of the legislation was to allow them to serve in the military so long as their sexuality was kept a secret.
In my view the best word would be ethos. Ethos is the set of fundamental values, guiding principles, social practices and beliefs that constitute the character of a particular culture.
