iPhone 6S Plus logic board layout as a .bvr boardview, file size 323 KB. No board number or revision is given in the name, so check that the component placement corresponds with the board you are repairing. A boardview of this kind lets a technician click a part to see its net, follow rails from the battery connector through the power management chips and pick reliable test points. Typical uses include locating a short on the main supply, checking touch and display connector lines and verifying continuity after removing a chip.
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.