Reference sheet for the 2N4264, saved as a 264 KB PDF and carrying an RE tag in the file name that is not explained further. Although indexed as a schematic, a 2N-numbered file like this is normally a component datasheet. Repair work typically draws on it for lead identification, electrical limits and characteristic curves when checking a suspected failed part with a multimeter or choosing a replacement. Because 2N numbers are produced by several vendors, confirm the package type printed on the board before soldering.
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.