The largest of this set at 474 KB, this PDF is named for the 2SC5097 and nothing more. The 2SC designation, under Japanese JEITA rules, belongs to NPN bipolar transistors, so the file should be a datasheet with ratings, characteristic curves and package details despite its schematic label. No manufacturer or package is given. Technicians consult such sheets to pin out an unknown part, check for shorts between junctions, and make sure any replacement matches or exceeds the original specifications.
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.