The 2SK690 is named here, and the 2SK prefix marks a Japanese-registered N-channel FET, so this 32.6 KB PDF is best treated as a part datasheet even though it is filed as a schematic. Expect a compact page or two with package outline, pin assignment and key ratings. When a transistor of this type fails on a board, the sheet helps identify the pins, verify breakdown voltage and current figures, and pick an equivalent with matching or better specifications before soldering in a replacement.
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.