Covering the 2sk2571, this 24.5 KB PDF is a short document classed as a schematic, though its name is just a part number and the content is likely a concise datasheet. The 2SK prefix denotes an N-channel field-effect transistor in the Japanese JIS system. Expect pinout and principal ratings rather than extensive curves. It serves for quick identification during diagnosis and when sourcing an equivalent transistor. Check that the code and package on the installed component match this designation first.
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.