Datasheet-style PDF of 44.0 KB for the 2SC4391, filed as a schematic; the trailing _E suffix in the name is not explained and could denote an edition or language version. The 2SC prefix is the JIS designation for an NPN bipolar transistor. No maker or package appears. Technicians use such a sheet to check lead order, voltage and current limits and the package drawing when testing or replacing the part. Make sure the number and suffix on the installed transistor match before substituting.
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.