Datasheet for the 2SD2271 transistor, a 219 KB PDF and one of the larger files in this 2SD group, so it probably includes detailed characteristic curves. Parts with the 2SD prefix are NPN bipolar transistors registered under the Japanese JIS system. Use the document to check pinout, breakdown voltages, collector current and gain when diagnosing or replacing the device. Check the printed marking and package on the board before relying on the pin order, since outlines differ between suppliers.
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.