The 2SK1442 is the sole detail in the name of this 107 KB PDF, which is categorised as a schematic. Following the JIS system, 2SK designates an N-channel FET, so the file most plausibly holds the component data sheet. It is useful for working out gate, drain and source before diode-mode tests, and for comparing ratings when a direct replacement is hard to find. Verify that the device on the board carries this exact number, since package and maker are not given.
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.