A 4.5 MB RAR archive carrying Apple iPhone 5 material. The name lists neither a board number nor the content type, so open it to see whether it holds schematics, boardview data or other service files. Such documentation helps trace power rails, locate filters and connectors, measure test points and diagnose faults like no backlight or no charging. Schematics read in a PDF viewer, boardview files in tools such as OpenBoardView. Check that the logic board in hand matches the iPhone 5 revision covered.
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 @cyberlanelectonik. 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.