Component document for the 2SK2611, a part number in the Japanese JIS scheme where the 2SK prefix marks an N-channel field-effect transistor. Although it is filed as a schematic, the name is just a part number, so it is most likely the device datasheet, here a 408 KB PDF. Technicians use such a sheet to check pinout, package, voltage and current ratings and on-resistance before choosing a substitute. Confirm the marking on the actual part matches, as similar numbers can differ in package or ratings.
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.