Labelled 30epf02, this 160 KB PDF is listed as a schematic but the name reads as a part number for a discrete power diode or rectifier. The file name gives no maker, model or board reference. Use it as a datasheet to check voltage and current ratings, recovery characteristics, package type and lead assignment. That is needed when testing a component in a switching supply or choosing a replacement with equal or better ratings. Make sure the marking on the faulty part really matches this number.
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.