This 105 KB PDF is named after the 2SC4159 and, although stored as a schematic, should contain the specification sheet for that NPN bipolar transistor, as the JIS 2SC prefix indicates. Components of this type typically show C4159 printed on the package. A repair technician uses the data to locate base, collector and emitter, compare measured junction behaviour against expectations and evaluate equivalents by voltage, current and gain. The file name lists no manufacturer or version, so verify marking, suffix and package against the actual part.
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.