A roman front matter before a decimal body is one page style before another
in ODF and one w:pgNumType per section in Word, not a document setting — read
as one, its pages printed 1, 3 where the reference prints i, iii. HfSet grows
pageNumberFormat, both exports write it back, and the DOCX importer takes the
document's own format from the first section, as it already does the paper.