A small PDF filed as a schematic, though the name is simply the part number 2SC3468, which follows the Japanese JIS semiconductor scheme where the 2SC prefix marks an NPN bipolar transistor. At 140 KB it is most likely a datasheet sheet rather than a board drawing. Technicians use such a document to confirm pinout, package and maximum ratings before fitting a replacement. Check the marking on the actual part, since the 2SC prefix is often dropped and only C3468 is printed on the body.
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.