MSI MS-6723 material packed in a 2.64 MB zip archive. Beyond the MSI project number the name says nothing, so the exact contents have to be checked after extraction. A file of this size could contain a scanned or exported schematic used to follow voltage regulators, clock lines and reset signals, or a firmware image for the board. The MS- code is MSI's own numbering and is printed on the PCB along with a revision, which should match whatever documentation is inside before you rely 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 @IT_SERVICE_WORLD. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.