PDF schematic for a sub board, labelled A015 and marked ORG, which typically indicates an original rather than redrawn document. The model is not spelled out beyond the A015 code, so confirm it against the part number printed on the small daughter PCB. A sub board of this kind normally carries the charging port, microphone and related connectors, and the drawing helps trace the USB, VBUS and audio lines back to the flex connector. At 1.44 MB it opens in any ordinary PDF reader.
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 @phoneSchematics. 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.