Apple iPhone 6 boardview in the .bvr format, 313 KB. Only the model is stated in the name; there is no board number or revision, so confirm that it matches the phone you are working on and is not the 6 Plus or 6S layout. A boardview maps components and nets, allowing you to search by designator, highlight every point on a rail and pick test locations for voltage or diode-mode readings. It is useful for touch IC, charging, backlight and no-power faults, especially when used together with a matching schematic.
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 .bvr file
Text boardview from the BoardView R family of tools, seen for Lenovo, MSI and Clevo boards.