Part reference for the 2SC1518 in a 51.5 KB PDF carrying an _E suffix, filed under schematics. Following JIS conventions, the 2SC prefix identifies an NPN bipolar transistor, so the file most likely holds the datasheet rather than a circuit diagram. Technicians consult it to identify emitter, base and collector, read absolute maximum ratings and judge whether an available substitute is suitable. Check any rank letter and the package on the physical part, since these determine which table values apply.
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.