Top-side component placement drawing in PDF for the MI2 board at the P4 build stage, most likely the Xiaomi Mi 2 phone. At under 10 KB it is a small vector layout rather than a full circuit diagram, showing outlines and reference designators on the upper PCB face. Technicians pair such a placement sheet with the matching schematic to find a part named in the circuit, locate test points and see where to probe. Confirm the P4 marking on the board before trusting positions, since earlier builds may differ.
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 @mobileschematicshub. 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.