Reference document for the 2SC3112 transistor, supplied as a 257 KB PDF and filed under schematics. The name holds only the part number. In JIS terms, a 2SC code identifies an NPN bipolar device of the high-frequency class. A datasheet like this is used to read the base, collector and emitter pin order, absolute maximum ratings and hFE ranges when testing or substituting the part. Any PDF reader opens it, and the body marking should be compared with the part before ordering a substitute.
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.