PDF of 187 KB carrying only the name Richtek, a maker of power management ICs such as PWM controllers, buck regulators and charger chips common on laptop and desktop boards. The name gives no part number, so the exact device covered is unknown until opened. A document like this is used to read pinouts, check enable and feedback pins, and confirm expected voltages around a regulator. Compare the marking on the chip, often a short top-mark code, with the document before relying on pin assignments.
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 @LaptopsBoardview. 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.