Datasheet for the 2SA970, supplied as a 321 KB PDF, the largest in this group, which suggests it includes detailed characteristic curves. By JIS naming the 2SA prefix identifies a PNP bipolar transistor. Technicians use the document to read maximum ratings, noise and gain data where given, and the pinout of the package. It is helpful for testing a suspect device, locating its leads on the board and finding an equivalent part. Confirm the marking and package before relying on 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.