What is prayer?

No, this isn't a philosophical question. On our vacancies page we classify our jobs into various areas we call domains. Internally we have 37 different domains, but that's too many to put in a dropdown list so map them to things that make sense (we hope) to people outside. For example anthropology, ethnomusicalogy, sociolinguistics and translation are all grouped as "language related". 

Recently some new domains were setup, like Sign Languages and Vernacular Media (i.e. media in people's own language). Until I get the word from the people who worry about these things I have mapped these to "language related" to. But what do I map "prayer" to?

For the sake of preventing an error message I've mapped it to personnel. What would you choose?