The 2SC5459 comes as a 186 KB PDF in the schematic category, though the part number, a JIS 2SC NPN transistor, points to a datasheet. Expect pinout, outline drawing, absolute maximum ratings and characteristic graphs. Repairers consult it when replacing a shorted transistor or checking whether a proposed substitute has adequate voltage, current and gain. Always match the marking and package on the board, and confirm the pin orientation in the sheet before soldering a new 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.