PDF reference for the IRFP90N20D power MOSFET, with the name noting a 200 V rating and 94 A current. Although indexed as a schematic, the 93.6 KB file is most likely the part datasheet with electrical characteristics, curves and the pin layout. Technicians consult it to identify gate, drain and source, judge whether a replacement can handle the same voltage and current, and check gate charge for driver compatibility. Note that the headline current is usually specified at a low case temperature, so allow margin in real circuits.
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.