EDITOR:I recently sent out 25 invitation for one of those "home parties." I sent the invitations two weeks prior to the event with a "Please, Please RSVP!" To date I have only received one response out of the 25 invitations sent out. I'm starting to think that most people don't know what RSVP means.With the holidays nearing and many people having parties, this may refresh the minds of many the proper etiquette for responding to invitations.In the context of social invitations RSVP or Rsvp is a request for a response from the invited person. It is an initialism derived from …