For you ARPs. I am perplexed about the history of the current edition of your standards. In 1976 an edition was published of 255 pages; sometime later an edition of 273 pages was created, which is the length of the current edition; I have copies 1998 and forward. A friend owns a 273 pager dated 1976 but has dated changes to after 1984. Searching online card catalogs, if the records are accurate, indicate the 255 page edition persisted at least through 1989. Anyone know the history here? ARPs, what date editions do you own?