Named simply 2SC4984, this 48.8 KB PDF is catalogued as a schematic yet points to a discrete semiconductor. The 2SC prefix, according to Japanese JIS/JEITA designation rules, marks an NPN bipolar transistor, so expect a compact datasheet. Typical contents include collector-emitter and collector-base voltage limits, current rating, gain and the case outline with pin numbering. Technicians rely on it when a suspect transistor must be checked in or out of circuit, or when sourcing a compatible substitute for a damaged board.
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.