RAR archive for the IBM ThinkPad X40 and X41, listed under Lenovo, about 1.84 MB. The name covers both models but does not state the contents or board numbers, so extract it with WinRAR or 7-Zip and check which documents are included. Material like this is typically used to follow power rails, check signal paths and track down a short on the motherboard. Because the two models differ, confirm that the drawing or layout matches the board number and revision printed on your PCB.
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.