Invitation initials

• BBQ invite letters
• Invitation notation
• Invitation advisory, or a homophonic hint to the starred answers' starts
• Abbr. in many a party invitation
• Setup provider's abbr
• "No alcohol provided" letters
• Part of an invitation to an imbiber
• Abbr. often near "R.S.V.P."

Wikipedia Word definitions in Wikipedia
BYOB is an initialism used on party invitations, meaning "bring your own beverage" or variants. BYOB may also refer to: BYOB (musician) , an English musician B.Y.O.B. (song) , a song by System of a Down from their album Mezmerize BYOB (programming language) ...

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
initialism (acronym) for "bring your own bottle" or "bring your own booze," by 1951.