Archive linked to the ASUS CS-B board, a 398 KB RAR file whose name does not state the document type. It may contain a schematic, BIOS image or other service data for this desktop motherboard. Open it with WinRAR or 7-Zip and check what is inside before starting work. Service files like this help when following signals, measuring rails against expected voltages, or reprogramming a damaged BIOS. Make sure the model and revision on the board itself agree with the files, and keep a copy of the original chip contents.
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 @boardview. 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.