The name of this 150 KB PDF gives only 2SC4409, a JIS-style part number where 2SC stands for an NPN bipolar transistor. Although filed among schematics, the document is most likely the component datasheet, listing electrical characteristics, maximum ratings and package dimensions. Technicians use it to confirm pinout before diode-mode testing and to judge whether an equivalent part is suitable. Opens in any PDF reader; verify that the code on the actual component matches before relying on the specifications.
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.