Listed under schematics, this 173 KB PDF is labelled only with the transistor number 2SC3423. In Japanese JIS numbering the 2SC prefix denotes an NPN bipolar device, so the file is presumably its datasheet. On the repair bench it confirms pinout for in-circuit diode testing, supplies the absolute maximum ratings, and helps compare candidate substitutes. The file name carries no package or manufacturer information, so check the case style and marking, usually C3423, on the original 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.