Compact 44.8 KB PDF for the 2SD1051, with an _E suffix in the name whose meaning is not stated, possibly a language or edition marker. It sits in the schematic category, but the 2SD prefix under the Japanese JIS scheme indicates an NPN transistor for low-frequency use, so treat it as a component datasheet. It helps when confirming pinout, maximum collector voltage and current, and gain grouping, and when comparing the original against equivalents during repair of amplifier or regulator circuits.
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.