For the 2SK1905 N-channel field-effect transistor, this PDF of 92.7 KB is indexed under schematics, though a bare part number in the name points to a datasheet. The 2SK prefix follows the Japanese JIS registration system. Technicians consult such sheets to identify gate, drain and source, read maximum drain-source voltage and current, and compare candidates for replacement. The name gives no manufacturer or package, so compare the marking on the original part with the drawing in the document.
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.