PF Japan shows the nomenclature with the schematics. This one, a typical C3, should suffice for most queries. It's been a concern for years for folks, with no nomenclature on the drawings.
With respect and without malice: When folks call parts other than what they are factory called, it gets confusing. Ergo: There is no bridge, set plate, etc, in a Common Abu. The Pure Fishing Japan site shows most of the rest of the family as well...5000's 7000's etc.http://www.purefishing.jp/parts_list/pdf/6500/1115458_AMB_6500C3.pdf