The 2SA1202 is covered by this 112 KB PDF, which the index lists as a schematic; with only the part code in the name, it is most likely the component datasheet. JIS designations beginning with 2SA refer to PNP bipolar transistors. A technician uses the ratings, characteristic curves and pinout to check a suspected faulty device and choose a suitable equivalent. Confirm the marking and any gain suffix on the original part, and check the orientation on the PCB footprint before fitting the new one.
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.