Listed as a schematic, this 105 KB PDF is named only after the 2SK1430 transistor and is probably its datasheet. Japanese JIS designations beginning 2SK indicate N-channel field-effect devices. The file name provides no further specifics such as package or voltage class. Technicians consult this kind of document for pinout, breakdown voltage, drain current and on-resistance figures, which help in confirming a failure and in choosing a replacement whose ratings are equal to or higher than the original.
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.