Compact 51.7 KB PDF documenting the 2N4036, filed under schematics though its JEDEC-style name indicates a discrete component datasheet. No manufacturer or edition is given. Such a document is used to confirm lead assignment, read voltage, current and power limits, and evaluate replacements when the original part is unobtainable. Keep in mind that 2N numbers are multi-sourced, so verify the case type and markings on the board against the drawing before trusting the pin layout shown.
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.