Listed among schematics, this 155 KB PDF is named after the transistor type 2SC3788 and gives no further details such as maker or case. The 2SC prefix, from the Japanese JIS standard, marks an NPN transistor, so expect a datasheet with ratings, characteristics and pin diagram. It is handy for in-circuit checks, for confirming lead orientation before fitting a new part and for qualifying a substitute. Any PDF reader will open it; verify the marking on the board component first.
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.