Datasheet-style document for the 2SJ537, delivered as a 137 KB PDF though indexed as a schematic. JIS numbering uses 2SJ for P-channel FETs, so the file most likely describes one transistor rather than a device board. Its practical value lies in the ratings tables, characteristic curves and pin diagram that let a technician check whether a part is within spec, test it out of circuit, or find a cross-reference. The name states no manufacturer or package, so compare the drawing with the component in front of you.
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.