PDF document for the 2SK715 part number, catalogued under schematics but almost certainly a component datasheet, since the 2SK prefix follows the Japanese JIS designation for N-channel field-effect transistors. At 90.3 KB it is a short sheet, likely covering pinout, absolute maximum ratings and electrical characteristics. Technicians use such sheets to confirm gate, drain and source pins, compare voltage and current limits when choosing a substitute, and check a suspected shorted transistor with a meter. Any PDF reader opens it.
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.