PDF document for the 2SK2846, filed as a schematic but named after a discrete semiconductor part number. Under the Japanese JIS naming system the 2SK prefix marks an N-channel field-effect transistor, so the 408 KB file is most likely the component datasheet. Technicians use such a sheet to confirm pinout, package, voltage and current ratings before fitting a replacement MOSFET. Check the marking on the failed part against the document, and compare ratings carefully when choosing a substitute.
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.