Filed as a schematic, this 81.8 KB PDF covers the 2N6520 and carries a Sam tag in brackets, which likely identifies the source or vendor of this edition, though the name does not spell it out. Parts with 2N numbers are JEDEC-registered discrete semiconductors, so the content is expected to be datasheet material: pinout, package drawing, ratings and typical curves. Different manufacturers publish slightly different limits, so check this copy against the plain 2N6520 sheet when choosing a replacement or substitute.
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.
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The standard format for schematics, block diagrams, power-sequence charts and service manuals.