A 56.1 KB PDF for the 2N3704, a JEDEC-registered 2N-numbered transistor, indexed as a schematic though it is a part datasheet. The name carries no maker, package or revision information. On the bench it helps identify which leg is base, collector and emitter, and gives the voltage and current limits needed to judge a substitute. Note that small-signal parts of the same number can ship in different lead orders from different vendors, so confirm against the actual component.
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.