PDF reference sheet, 40.2 KB, for the 2SA1252 PNP transistor; 2SA is the JIS prefix used for that device type. Indexed as a schematic, it is better understood as a datasheet since the name gives nothing but the part code. Contents typically include pinout, package dimensions and electrical characteristics. Technicians open it in a standard PDF reader to confirm base, collector and emitter positions, review ratings for a substitute, and avoid fitting a part reversed on the board.
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.