Part documentation for the 1SS400, an 86.6 KB PDF classed as a schematic. The 1SS designation belongs to the Japanese family of small-signal silicon diodes, so expect a datasheet with ratings and package drawings rather than a circuit diagram. The name gives no model, brand or board number. Technicians keep files like this to match tiny SMD marking codes to real part numbers, check pinout and polarity, and pick valid substitutes. Compare the footprint on your board with the package outline before replacing anything.
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.