Reference PDF of 113 KB for the 2SC3145 transistor, catalogued under schematics. Per JIS conventions, 2SC identifies an NPN bipolar device, generally stamped C3145 on the package. The file name holds no further detail such as manufacturer or package, so those come from the sheet itself. It is useful for confirming which lead is collector, base and emitter, for checking absolute maximum ratings against the operating rail, and for picking a cross-reference replacement with matching or higher limits and the same footprint.
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.