Brief 41.9 KB PDF for the 2SC5453, in the JIS 2SC range that denotes NPN transistors. Catalogued as a schematic, it is most plausibly a short datasheet covering the pinout, package and main electrical ratings. When a transistor tests faulty, the sheet helps confirm what was fitted and what can replace it. Check that the package matches the PCB footprint, verify the pin order, and make sure the voltage and current ratings of any substitute are not lower than the original.
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.