The 2SD1111 is the only detail in the name of this 71.5 KB PDF, indexed as a schematic but best read as the transistor datasheet. Japanese JIS designations beginning with 2SD cover NPN bipolar transistors for low-frequency applications. Inside you can expect ratings, characteristic data and package dimensions. Use them to identify leads, test the part with a meter in diode mode, and confirm that any substitute matches the polarity, package and electrical limits.
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.