Named simply 2SC3447, this 97.5 KB PDF appears under schematics but is most likely the transistor's datasheet. Japanese JIS numbering uses the 2SC prefix for NPN bipolar devices. A technician uses such a sheet to confirm lead order before in-circuit testing with a diode meter, to look up maximum ratings and to judge whether a cross-referenced equivalent is safe to fit. The file name says nothing about package or manufacturer, so verify those against 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.