A 101 KB PDF carrying only the part number 2SK223. Following JIS conventions, 2SK marks an N-channel FET, so the document is likely a datasheet although categorized as a schematic. It should list pinout, package, maximum drain-source voltage, drain current and power dissipation. During repair it helps verify whether the component is shorted or open, and when sourcing an equivalent confirm footprint and lead sequence so the substitute drops into the board correctly.
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.