Small 506 KB RAR archive linked to the Xiaomi Mi 1S phone. Apart from the model, the name says nothing about the contents, so identify the document type after unpacking. Repair data of this sort is normally used at board level to read circuits, trace rails and signal lines, locate components and test points, and narrow down shorts. The Mi 1S is an updated version of the Mi 1, so make sure the board markings on the handset correspond to the files before using values or layouts from them.
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 @SMART_PHONE_SCHEMATICS. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.