Catalogued as a schematic, this 69.5 KB PDF is named after the part number 1SS381, so it is most likely a component data sheet. In the Japanese JIS scheme the 1SS prefix marks a small-signal silicon diode. A technician would check it for pinout, package marking, forward voltage and reverse ratings before fitting a replacement diode on a board. Any PDF reader opens it. Match the package code and marking on the faulty part with the drawing in the document before relying 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.