The 2SC4163 part number is all this 98.9 KB PDF name reveals, so although labelled a schematic it is best read as a transistor datasheet. The JIS 2SC prefix denotes an NPN bipolar device, usually marked C4163 on the board. Typical uses include confirming pinout before measuring junctions with a multimeter, checking voltage and power limits, and finding a suitable cross-reference part. Neither the manufacturer nor a document revision is given, so match the package outline and marking of the installed component before trusting the figures.
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.