Filed as a schematic, this 326 KB PDF carries the part number 12CLQ150 and is most likely the component datasheet for that device. Its name follows the International Rectifier naming style used for rectifier parts. The larger size hints at extra curves or package drawings. Use it to check voltage and current limits, pin assignment and mounting details when replacing a damaged component, and always compare the full marking on the part with the code listed in the datasheet.
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.