The 2SC1359 named in this 55.6 KB PDF is, by its 2SC prefix, a Japanese-standard NPN bipolar transistor, so despite the schematic label the document should be a component datasheet. An _E suffix usually marks the English version. A technician opens it in any PDF reader to look up the package drawing and terminal order, the maximum collector-emitter voltage, current and dissipation, and the hFE ranks. Those numbers decide whether a cross-reference part is a safe drop-in replacement on the board being repaired.
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.