RAR archive of 1.31 MB for the IBM ThinkPad X61 ultraportable, produced in the era when the line had moved to Lenovo though it is still often labelled IBM. The name gives no board number or revision, and the contents, likely a schematic, should be confirmed after extraction. Use it to trace the power rails, the charging circuit and the power-on sequence, and to locate test points. Check the planar markings, since X61 boards came in more than one variant.
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 .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.
7-ZipWinRARThe Unarchiver (macOS)