What is the french response for RSVP?

RSVP is an abbreviation asking you to reply, often to an invitation. In many cases the invitation carries a stub with the number of persons who will attend (or decline to attend) the event and you just send that back. In the other cases you often indicate through the contact provided (phone number, mail address), what is your response to the answer on the invitation. Common replies are extremely various. That may be : 'cher ami, je ne pourrai malheureusement pas être présent pour ... ' (Dear, I regretfully won't be able to attend ... (event) or 'nous viendrons tous les deux avec plaisir' (we will both be here). Short and simple answers are common and perfectly acceptable.