Apple iPhone 6S repair archive, packed as RAR and 3.57 MB in size. The file name does not state what it holds, so expect typical logic board documentation such as a schematic PDF or boardview, and confirm after opening. A technician uses this material to follow power rails from the PMIC, identify filters and coils near a fault, locate test points and compare readings against known good values. Viewer software like OpenBoardView handles common boardview formats; verify the board number before trusting component locations.
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.