At 188 KB, this PDF named 2SC4640 most likely holds the datasheet for that Japanese-standard NPN transistor. No equipment, board number or revision appears in the name. Datasheets of this kind specify absolute limits, gain classes, saturation voltages and thermal data, with a dimensioned package outline. A technician uses them to verify the pin layout before installation and to compare ratings when cross-referencing a replacement. Check that the part code and package on the board match the document before relying on it.
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.