Small RAR archive of 214 KB named after the P5P43TD, an ASUS desktop motherboard model; the name gives no file type or revision, so the contents need to be inspected after extraction. Archives of this size labelled with a bare board model often hold a boardview in FZ or similar format, used to locate components, pins and test points on the PCB. ASUS FZ files open in viewers such as OpenBoardView or FlexBV. Check the revision printed near the PCIe slots against any version shown inside before measuring.
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.