Schematic PDF named U56E with an RG suffix, most likely an Asus U56E laptop circuit diagram, though the brand is not stated in the name and the meaning of RG is unclear. At 518 KB it may be a partial or compressed set, so review the page index before relying on it. Schematics like this support tracing power rails, checking enable signals and finding parts tied to a shorted line. Confirm the board name and revision printed on your mainboard matches what the title block shows.
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.