Schematic diagram in PDF form for the ASUS UX430UQ laptop mainboard; the RG suffix in the name is not explained and no board revision is given. Technicians use a schematic like this to trace power rails, follow enable and power-good signals through the startup sequence, and identify which component sits on a shorted line. Any PDF reader opens it and the text is usually searchable for net names. Compare the revision printed on the page footer with the silkscreen on the PCB before relying on part values or values of resistors in the circuit.
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 @boardviews_schematics. 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.