Filed among schematics, this 206 KB PDF is named 82CNQ030A, a code in the International Rectifier dual Schottky diode format, with an A suffix that denotes a variant of the base part. Treat it as a component datasheet, not a board diagram. It helps when a rectifier in a power stage is suspected of leakage or short: read the pinout, expected forward drop and absolute limits, then measure. A separate copy without the suffix exists, so check which version your part carries.
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.