A 31.3 KB PDF for the 2SC5764, stored with the schematics. The name contains just the semiconductor part number; in Japanese numbering, 2SC identifies an NPN transistor designed for high-frequency work, so this is most likely a brief datasheet. Technicians use it to look up the SMD marking, pin configuration and electrical limits while testing a suspect transistor or selecting a replacement. Confirm that the package and marking printed on the component agree with the document before acting on 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.