The dining in is a formal event for all unit members, male and female; though some specialized mess nights can be officer- or enlisted-only. The unit chaplain is usually also invited, if an invocation is needed. A unit's dining-in consists of only the members of the unit, with the possible exception of the guest(s) of honor. An optional formal dinner, known as the dining-out may include spouses and other guests. The dining-out follows the same basic rules of the dining-in, but is often tailored to minimize some of the military traditions and be more approachable to civilian guests.