Covering the 1SS394, this 66.2 KB PDF is filed as a schematic but most likely holds a component datasheet, since 1SS denotes Japanese-registered small-signal silicon diodes. The name does not mention any device, brand or revision. Expect electrical characteristics, absolute maximum ratings, package outline and marking information. That data is useful for confirming polarity, judging a diode-mode reading or finding a replacement with suitable ratings. Any PDF viewer will open it. Match the package type on the PCB before ordering parts.
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.