PDF document for the 2SD1995 semiconductor, catalogued under schematics but by its name a component datasheet. Under the Japanese JIS scheme, a 2SD prefix marks an NPN bipolar transistor intended for low-frequency use. The trailing E is not explained in the name and may mark an edition. At 45.5 KB it is likely a short sheet covering ratings, pinout and package outline. Technicians use such data to confirm voltage and current limits and pin order before fitting a replacement.
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.