Catalogued as a schematic, this 203 KB PDF named 87cnq020a is most likely a datasheet for a low-voltage dual Schottky rectifier module, the 020 typically denoting a 20 V reverse rating and the a suffix a revision. The manufacturer is not stated. Low-voltage parts of this kind sit in high-current output stages, so the sheet helps check forward drop, current and thermal figures. Measure the suspect diode first, and never substitute a part with a lower voltage or current rating than listed.
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.