Small PDF of 58.8 KB catalogued as a schematic, whose name carries only the part code 30CPH06 and no brand, board or revision. A name of this kind usually points to a component datasheet rather than a full board diagram, most likely a power rectifier document, though that should be confirmed by opening it. Technicians keep such sheets to check pinout, voltage and current ratings and package markings before replacing a shorted diode on a board. Any PDF reader opens it; compare the marking on the part with the document first.
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.