[DemchaAV]

Why

A text header or footer (DocumentHeaderFooter) is written as one exact line of a Word header or
footer: its left slot, its centre slot at a centre tab and its right slot at a right tab, page tokens
as fields. Measured in Word 16 and LibreOffice on Windows, four things showed otherwise than on the
page, and the report said nothing.

Case	Page	Word	LibreOffice
9pt text, header 11pt tall	baseline 6.5pt from the top	8.64	8.60
9pt text, header 13pt tall	8.5	8.64	8.60
9pt text, footer 10pt tall	baseline 1.0pt from the foot	2.04	2.21
that footer's 0.5pt separator	10.0pt from the foot	10.92	11.06
header 14pt, footer 12pt tall	—	where the page sets them	where the page sets them
lettered numbers: page 27 / 28 / 53, total of 56	aa / ab / ba, bd	aa / bb / aaa, ddd	aa / ab / ba, bd
left slot reaching past the centre slot's start	drawn over one another	centre and right set after it, right at x=360, past the 328 margin	the same
centre slot reaching the right slot's start	drawn over one another	right set after it, past the margin	right on a line below
one slot wider than the line	runs past the margins	wrapped onto a line below	wrapped onto a line below

The line is exact and starts at the page's edge. A shorter line, or text raised in it, would cut its
letters: Word draws an exact line's text only inside the line on screen.

What changed

• DocxTextBands:
  • baselineFromEdge: where the page sets the baseline;
  • baselineMovedIn: how much further in Word stands it, where the line stops at the edge;
  • separatorMovedIn: the separator ruled past a line taller than its band;
  • slotsOverlap: the page's three slot positions against one another.
  • distanceFromEdge(band) now reads baselineFromEdge; same arithmetic, the corpus is byte-identical.
• DocxSemanticBackend.reportBandText, given once per band from its writer: APPROXIMATED
  notes, subject page header / page footer:
  • a shallow band, with about how far its text moves, and its separator where it moves too, at
    0.1pt or more;
  • a band numbering in letters (LOWER_ALPHA / UPPER_ALPHA) with a {page} or {pages} token,
    where the layout runs to 28 pages or more, or with no layout behind it, "where the document
    runs that far";
  • overlapping slots, and a slot wider than the line, "on every page it is drawn on" or "on N of
    the M pages".
• slotsSetOn reads each page the band is drawn on as the page does:
  • its numbering's offset and first page;
  • its tokens resolved for that page;
  • its width in the band's face, or in Helvetica, which the page draws a face its fonts lack in;
  • with no layout, the first page it is drawn on;
  • a band with no page token once.
• Docs:
  • the DOCX recipe's text header section;
  • the capability matrix's header row;
  • DocxNodeFieldLedgerTest's headersAndFooters entry;
  • CHANGELOG v2.5.0.

Verification

• DocxBandTextReportTest (new, 9 tests):
  • header 11pt (2.1pt) and 13pt (0.1pt), footer 10pt (1.2pt), each worded;
  • the footer's separator (1.0pt), and a header whose line fits no separator clause;
  • header 14pt and footer 12pt named nothing;
  • letters: 28 pages named for {page} and {pages}; 27 pages, roman numbers and a band with no
    token not named; no layout hedged;
  • overlap of left and centre, and of left and right with no centre; a short control not named;
  • on 3 of 12 pages, and on 3 of 11 when kept off the first page (widths built from Helvetica so a
    digit more on page 10 makes the overlap);
  • a slot wider than the line;
  • no layout with the band off page 1.
• DocxTextBandsTest (+4): the shifts, the separator, the overlap geometry.
• 18 sabotages, each undoing one part, all caught: each note, the threshold, the header and footer
  shares, page 28, the token and letter conditions, the no-layout branches, the first page counted,
  each overlap edge, unread tokens, the separator's width, a band read once counted once, a wide
  slot unmeasured.
• Corpus: 62/62 DOCX byte-identical; report notes 1246 → 1246.
• ./mvnw -B -ntp clean verify: BUILD SUCCESS (core 821, render-docx 1793, examples 93, qa 1820); the knowledge pack's --check passes.

Lane: render-docx (semantic backend). Report notes only; no output change.