Datasheet PDF for the 2N4031 part number, 52.3 KB in size, placed in the schematic category of the index. The file name provides only the JEDEC number, without vendor or revision. Expect a pinout diagram, package outline, maximum ratings and electrical characteristics, which is what a repair tech needs to test the device out of circuit or find a workable equivalent. Since multiple makers produced parts under this number, confirm the case style on the board before following the pin order.
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.