A 316 KB PDF dedicated to the 2SK2401, sorted under schematics but most likely a part datasheet given its JIS-format number; 2SK designates an N-channel FET. Manufacturer, package and voltage rating are not part of the name and should be taken from the document. It serves when a transistor in a supply or switching stage has failed short, helping to match pin layout, drain current, breakdown voltage and on-resistance so that any substitute behaves the same in circuit.
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.