At only 34.3 KB, this PDF for 2SC4453 is probably a short datasheet of a page or two, even though it is catalogued as a schematic. The 2SC code belongs to the Japanese JIS system and indicates an NPN bipolar transistor for high-frequency use. The name offers no other details. Even a brief sheet usually gives the pinout, package and absolute maximum ratings, which are enough to verify a replacement and to interpret junction readings taken with a meter in diode mode.
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.