Schematic labeled T61, most likely the ThinkPad T61, as a 2.09 MB PDF; the name gives no board number, revision or graphics variant. The T61 was produced with both integrated and discrete graphics boards, so verify which one these drawings cover. Technicians use it to trace power rails, check the charger and regulators, follow signals and locate components near a short. Read the title block and compare the board identifier with the label on the motherboard before relying on its values.
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 @schematicslaptop. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.