The 2SK1449 gives this 109 KB PDF its name, and nothing else is stated. It is filed as a schematic, though it is probably the device data sheet. The 2SK prefix comes from the Japanese JIS register and designates an N-channel FET. For a technician, the value lies in the pinout diagram, breakdown voltage, drain current and switching data used when diagnosing a failed power transistor or approving an equivalent. Check the package and printed code on the board before relying on these figures.
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.