Larger than most of its neighbours at 123 KB, this PDF is named only 1SS313 and gives no device or board details. The 1SS prefix is the JIS code for small-signal diodes, a family widely produced by Toshiba, so the file is likely a datasheet, perhaps with extra curves or package drawings. Technicians consult it for polarity, maximum ratings, forward characteristics and marking code. Verify the package and marking on the PCB match before trusting it for a replacement or for diagnosing a shorted line.
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.