Only the series code 81CNQ appears in the name of this 125 KB PDF, suggesting a family datasheet covering several voltage grades of dual Schottky rectifiers in International Rectifier style. No device or board number is given, despite the schematic category. Family sheets are handy for seeing the common package, pinout and how ratings change across grades. Determine the exact grade from the part marking before taking values from the tables for testing or substitution.
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.