Filed as a schematic at 106 KB, this PDF bears only the identifier 2SC5070. That code belongs to the Japanese 2SC series of NPN transistors, so the document should be a component datasheet rather than a circuit diagram of a device. The name gives no manufacturer, package or revision. Open it in a PDF viewer to read absolute maximum ratings, hFE and frequency characteristics and the lead layout, which are what you need when testing in circuit or picking an equivalent part.
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.