RAR archive of roughly 2.11 MB covering the Lenovo B470 and B470C, with the name pointing to the Wistron LA470 platform design. The exact contents are not listed, but packages like this usually hold a schematic, a boardview or both for the mainboard. Wistron manufactured these Lenovo boards, so the reference material uses Wistron naming. Unpack it and check each file: schematics open in a PDF reader for rail tracing, boardviews need a viewer such as OpenBoardView. Match the board number printed on your PCB before relying on it.
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 @alischematics. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.