< RSVP >

RSVP : "Répondez S'il Vous Plaît", a French phrase that translates to "please respond" and word for word means "respond if you please". It is with this meaning that invitation cards and similar documents are often marked with "R.S.V.P." It is standard practice to reply to an RSVP request whether confirming attendance or declining.

http://en.wikipedia.org/wiki/Rsvp