The 2SC5088 transistor is the subject of this 481 KB PDF, catalogued as a schematic though it most likely holds the component datasheet. The name states only the part number, with no brand, package or version. Under the JIS system, 2SC marks an NPN bipolar transistor typically intended for high-frequency use. Technicians consult it for pinout, ratings and package dimensions while repairing or substituting. Bodies often show just C5088, so check marking and package match before soldering in a replacement.
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.