That is what they are called.
Get yours from Keith Bates, see details on his website:
Added by Ruud Janssen on November 11, 2012 at 9:23am — No Comments
Because I got the question I had to do some digging in the archive, As it turns out I found the starting month back in one of my own publications that I wrote in 1990:
This booklet was published in 1990 to document my first 10 years in Mail-Art. I still have the originals here. In it I wrote about the start of the IUOMA. It turns out to be AUGUST 1988. Later in…Continue