On an Amazon description of an rsvp pen I saw “Pentel introduced the first R.S.V.P. ballpoint pen in 1994”. The product on Amazon is listed by official Pentel store

Oh, wild! Was thinkin' that the RSVP was a nice one to write with back then, before I moved on to my 1st non-disposable pen (the Zebra F-605) - well, at least, I didn't dispose of it. Might actually have the RSVP around still as well (even though the refill's empty), lol

😎