Stored under schematics, this 93.8 KB PDF is named for the 2SC4123 and is expected to hold the transistor's datasheet rather than a circuit drawing. JIS numbering uses 2SC for NPN bipolar transistors, often abbreviated to C4123 on the package. Technicians use it to read pin assignment and package dimensions, check breakdown voltage and current ratings and judge whether an alternative part will fit and perform. The name states nothing about maker or revision, so compare the marking on the original device 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.