Reference sheet for the 2SD2385 transistor, delivered as a 180 KB PDF and indexed under schematics. Japanese JIS numbering reserves the 2SD prefix for NPN bipolar devices intended for low-frequency use. The name states nothing beyond the part number, so the content is presumably ratings, characteristic graphs and a package outline. Technicians use these figures to verify lead order, judge thermal and voltage margins and select a suitable equivalent when the original is unavailable.
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.