Greg and Debra Barnes discovered that someone was re-writing Hubbard bulletins and they they were excommunicated for making that discovery.
While they were doing Scientology's confidential upper OT level VII the Barnes were shown a technical bulletin (C/S series 73RB) that Scientology's new management claimed was written by Hubbard. The bulletin stated that the security checks (also called "refreshers") they and all persons auditing on OTVII were being forced to undergo each six months contradicted what Hubbard himself had directed about such processes. They also realized that C/S series 73RA was 12 pages long whereas the bulletin they were reading was only 5 pages long.
So, why is that important and what are all the numbers? C/S Series 73RA means that this was Hubbard's 73rd bulletin on Case Supervision of auditing processes; the "R" stands for "revised" - in other words, Hubbard may have changed some things in the bulletin after initially releasing it. The next letter shows how many times it was revised so in this case "A" indicates it was revised once; "73RB" means that the same bulletin was revised twice. That is important because the Barnes discovered that seven pages of Hubbard's instructions had been removed from the bulletin by Scientology's current management after Hubbard died in 1986. In Scientology, altering Hubbard's writings is a criminal offense, so the Barnes took it upon themselves to bring these alterations to the organization's attention.
The internal documents and reports listed on the Meet Greg and Debra Barnes page may be a little difficult for the "unitiated" to read but nonetheless, they offer a fascinating glimpse into how the organization conducts its internal affairs and the format in which Scientologists are instructed to resolve disputes and grievances, namely by writing reports.