Filed under schematics, this 173 KB PDF is named after the 2SA965, a part number in the Japanese JIS scheme where the 2SA prefix marks a PNP bipolar transistor, so it is most likely a component datasheet, not a board diagram. Expect pinout, package outline, absolute maximum ratings and hFE grading. Technicians use such a sheet to confirm a replacement or substitute part, identify base, collector and emitter before in-circuit testing, and check voltage and current limits. Any PDF reader opens it.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @cyberlanelectonik. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.