Part number 2SC4207 is the sole content of this 257 KB PDF's name, which the index places under schematics. Because JEITA uses the 2SC prefix for NPN bipolar transistors, the file is almost certainly that device's datasheet, giving ratings, hFE data, curves and mechanical dimensions. The manufacturer and package are not specified. Repair technicians rely on such data to identify terminals, interpret diode-test readings on a possibly shorted part, and confirm that a cross-reference replacement is electrically adequate.
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.