A 46.1 KB PDF filed under schematics that covers the 2SC4691 transistor. Under JIS numbering, 2SC identifies an NPN bipolar device, so expect a datasheet-style document rather than a board diagram. The E suffix in the name is not explained by anything else in it. On the bench it serves to check pin assignment, package and voltage or current limits when a shorted or open transistor has to be swapped. Any PDF reader opens it, and the marking on the original part should be verified against this number before choosing a replacement.
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.