Service material for the IBM ThinkPad R31, compressed into a 913 KB RAR file. The name states only the model, with no board number, revision or indication of whether the archive holds a schematic or other drawings. Once extracted, such documents let a technician follow power rails from the charger input through to the CPU and chipset, and locate parts when isolating a short. Older ThinkPad lines sometimes used several board variants, so compare the PCB markings with the document before relying on it.
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.