Reference sheet for the 2N3772 in a small 14.8 KB PDF, listed as a schematic but in practice a datasheet for a 2N-numbered transistor. The name gives no maker, revision or package detail, so the source vendor is unknown until opened. Technicians consult such a document when testing a suspect transistor with a meter, checking the base, emitter and collector layout, or confirming that a substitute meets the voltage, current and dissipation ratings. Any standard PDF reader will display it.
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.