Component documentation for the 2SC4220, delivered as a 106 KB PDF and filed under schematics. The file name offers only the part number, with no maker or package suffix. Under JEITA rules a 2SC type is an NPN bipolar transistor, so this should be its datasheet with electrical specifications and dimensions. It is useful for confirming pinout before an in-circuit diode test, checking power and voltage ratings against the circuit, and selecting a suitable substitute when the original is no longer stocked.
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.