A compact 44.5 KB PDF labelled 2SJ520 and catalogued as a schematic. Because 2SJ is the JIS prefix for P-channel FETs, the document is best treated as a short datasheet for that single part, possibly just a summary sheet given its small size. Technicians consult such a file to check pinout, package and key limits like drain-source voltage and continuous current when hunting a replacement or testing a suspect transistor. The name gives no device or board context, so match it against the marking on the component.
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.