Catalogued as a schematic, this 190 KB PDF is named after the 2SC2999, a part number in the Japanese JIS scheme where the 2SC prefix marks an NPN bipolar transistor. It is most likely the manufacturer datasheet for that device rather than a board diagram. Technicians use such a sheet to confirm the pinout, maximum ratings and hFE range before fitting a substitute. Check the marking and package on the faulty part first, since the same number can come in different packages from different makers.
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.