The 2SC4944 is the only detail carried by this 259 KB PDF, catalogued as a schematic. Since 2SC is the JIS/JEITA prefix for NPN bipolar transistors, the document should be a component datasheet, likely including graphs of characteristics given its size. Repair technicians consult it to locate base, collector and emitter on the package, read VCEO, IC and power dissipation limits, and select an equivalent part. Check the footprint and pin order before soldering in any substitute.
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.