Reference sheet for the 2SK315, stored as a 176 KB PDF and catalogued as a schematic. The JIS 2SK prefix denotes an N-channel field-effect transistor, so the document should describe one discrete device, not a full circuit board. Such a datasheet gives pinout, package outline, breakdown voltage and drain current limits plus characteristic curves. Repair work typically relies on it to verify a suspected failed FET and to pick a substitute with equal or better ratings and the same pin order.
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.