A schematic diagram for Apple hardware (board 820-00189). Shared as “iPhone 7 [820-00189] (Intel) Boardview.pdf” — a .pdf file, 492 KB.
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 @uzb4422. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.
Any PDF readerSumatraPDFFirefox / ChromeFlexBV (links PDF to boardview)