Named after the 2SK1425 transistor, this 102 KB PDF is catalogued as a schematic though it is most probably the component datasheet. Within JIS numbering, 2SK refers to N-channel FETs. Package type, maker and ratings are not part of the name and should be read from the file. Use it when you need the pin assignment for probing, the breakdown voltage and current limits for choosing a replacement, or the gate threshold to understand how the device is driven.
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.
Any PDF readerSumatraPDFFirefox / ChromeFlexBV (links PDF to boardview)