MS Office PKZip container ordering may leak information
modern MS Office .docx documents are PKzipped containers of XML.
the individual member elements of the PKZip archive might appear in any order, but different generators might put them in different order.
For example, i think that MS Office itself puts [Content_Types].xml
first, while LibreOffice puts it last.
mat2 should choose a canonical ordering and store the elements in that order.