A 50.2 KB PDF for the 2SC5566, sitting in the schematic section of the index. The name is a bare part number; the 2SC designation in Japanese semiconductor naming refers to an NPN transistor intended for high-frequency circuits, so expect a datasheet. Use it to confirm the collector, base and emitter pins, look up breakdown voltage and current limits, and compare gain classes when picking a replacement. Make sure the package drawing matches the device actually soldered on the board.
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.