ZIP archive for the IBM ThinkPad X31, about 1.90 MB. The name identifies only the model, with no board number, revision or description of the enclosed files, so unpack it with any standard archiver and review the contents. Packs like this commonly contain schematics or service documents used to trace power rails, locate components and check signal paths on the motherboard. Before relying on any drawing inside, compare its title block with the markings printed on the system board of the laptop being repaired.
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 @cyberlanelectonik. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.