RAR archive for the IBM ThinkPad A20 and A22 notebooks, around 3.8 MB. The name does not state a board number, revision or what the package contains, so extract it with 7-Zip or WinRAR first. Material for these early ThinkPad models typically helps with following power circuits, understanding power-up sequencing, finding components on shorted lines and locating measurement points. Several board variants existed across this family, so verify the board number or FRU printed on your system board before relying on the files.
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.