Small ZIP archive of 1.34 MB labelled only for the Xiaomi Mi 4 smartphone, with no code name, variant or document type stated. Several Mi 4 versions exist, including an LTE model, so check which one the contents describe before using them for diagnosis. Repair archives of this size usually carry schematic diagrams or board layout drawings, which let a technician trace power rails, locate test points and find replacement components. Extract the files and compare the board markings with your phone before trusting any part numbers or measurements.
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 @mischematic. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.