A 52.8 KB PDF labelled 1SS351, catalogued as a schematic though the name is just a component number. In the Japanese JIS scheme 1SS marks a small-signal silicon diode, so the document should give its ratings, electrical characteristics, pin connection and outline. It is useful when a diode reads shorted or open and must be replaced with a correct equivalent. Any PDF viewer will display it. Check that the marking and package of the part on the board match this device before relying on the data.
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.