For the 2SA1356, this 177 KB PDF carries just the part number, so it is most probably the device datasheet rather than a full circuit diagram. The 2SA prefix in the Japanese JIS system indicates a high-frequency PNP transistor. It is handy for confirming pin assignment and package, checking collector-emitter voltage and current limits and picking a replacement with matching gain. Expect the case to be marked A1356 without the 2S, and confirm that code before trusting the data.
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.