PDF covering the 2SK1104, an N-channel FET identified by the 2SK prefix of the Japanese semiconductor numbering system. The file name holds nothing beyond the part number, and the 28 KB size suggests a brief datasheet rather than a circuit diagram. It serves for checking pinout, maximum voltage and current, and switching characteristics when diagnosing a shorted or open transistor. Before substituting, measure the suspect part out of circuit and confirm the package and gate-drive requirements of any replacement match.
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.