Version of the 2N5401 high-voltage PNP transistor datasheet tagged Sam in the name, a 53.3 KB PDF. The tag most likely points to a Samsung-issued sheet, though the name alone does not confirm it. Contents normally include absolute maximum ratings, electrical characteristics, gain classification and the TO-92 outline. A technician uses it to verify pinout and limits when swapping parts from different suppliers. Having several vendor versions on hand is useful, because minor differences in specification and lead order do occur.
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.