PDF of 34.7 KB for the 2SA821S, one of the smallest documents in this group, with only the part number in its name. The 2SA prefix comes from JIS numbering and denotes a PNP bipolar transistor; the trailing S is part of the designation, and its meaning is not stated here. Contents are likely a compact datasheet with ratings and outline. Use it to confirm lead order and limits when replacing this part, and compare the exact suffix variant, since suffixed versions can differ in package or characteristics.
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.