Datasheet-style PDF for the 2SC3988, 114 KB, filed in the schematic category though the name is a plain JIS transistor number. The 2SC prefix identifies an NPN bipolar device in the Japanese numbering system. Technicians consult this kind of sheet for voltage, current and power limits, hFE classes and the mechanical drawing, especially when hunting a replacement or measuring a suspect part out of circuit. Check that the case type and the printed C3988 code 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.