Compressed package for the Lenovo ThinkPad X230, with the name naming Wistron as the board maker and Dasher as the project code. Wistron is the ODM behind many ThinkPad motherboards. No contents are listed, so extract it and check for a schematic or boardview. Such material helps trace power rails, follow enable and power-good signals and locate components near a short. Before relying on it, compare the board number on your PCB with the one in the document title block.
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.