Datasheet-style PDF for the 2SK3018, indexed here under schematics, though the 2SK prefix marks a Japanese JIS-registered N-channel field-effect transistor rather than a circuit diagram. At 108 KB it is a short component document. Technicians use such sheets to confirm the pinout, package and maximum voltage and current before fitting a replacement, and to judge whether a substitute part is safe. Check the marking on the board part against the document, since small packages often carry abbreviated codes.
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.