[DemchaAV]

Why

A Word border's w:sz runs from two to ninety-six eighths of a point, and the export held
every border to that range without a word in its report: a panel's borders (a section's, a
container's, a row's, a shape container's panel in a cell), a table cell's rules, a rule written
as a paragraph's border, and a text header's or footer's separator. A 20pt panel border was
written 12pt wide and a 0.1pt hairline a quarter of a point, while the report promises that
what the file does not hold is said. In the corpus, CompactMono's header rule is one:
stroked 0.1pt, written 0.25pt, unreported.

A separator of no width, which the PDF strokes with a line width of 0 — the thinnest line a
device shows — was not written at all, and one set below zero or to NaN was dropped silently.

What changed

• DocxBorderWidths (new, package-private): eighths(points) replaces the backend's
  ruleEighths at every place a border width becomes w:sz; notHeld(what, plural, widths)
  says which widths fall outside Word's range once rounded to the eighth Word counts in, and
  ofNoWidth(what) what a separator of no width becomes. A width that rounds to an eighth Word
  draws (0.2pt → two eighths) is drawn at it and not named.
• Notes (border width, APPROXIMATED): once for a panel (on its first piece, as its
  translucency note is), once for a table (its cells' rule widths collected across the grid,
  covered positions too, deduplicated), once for a rule, and once for a separator however many
  headers it is written into (separatorsReported, which now remembers the band for its width
  as well as its colour).
• Separator: separatorShown/separatorWritten decide it in one place. One of no width is
  written at Word's thinnest and named; its frame holds it, and reachOf — whether a band
  reaches past the page margin — now counts the separator as Word draws it, its width in
  eighths and nothing for one not written (it counted the page's thickness on
  showSeparator alone). One below zero or NaN is named (DROPPED) and not written.
• DocxNodeFieldLedgerTest: the border-width case is in the entries of a panel's, a row's, a
  table's and a shape container's borders, a line's stroke, a filled bar's height and the
  headersAndFooters option.
• Docs: the recipe (panel borders, the header and footer section), the capability matrix (the
  shape, line, table and header/footer rows), CHANGELOG v2.5.0 Public API.

Verification

• ./mvnw -B -ntp test -f render-docx/pom.xml — DocxBorderWidthsTest (new, 16): the eighths
  and the threshold (0.2pt and 12.06pt held; 0.001pt, 0.05pt, 0.1pt, 16pt and 20pt named,
  listed in order); a panel's 20pt border and a 0.1pt side (w:sz 96 and 2), a panel split by a
  page break named once, a row's border, a table's 0.05pt and 20pt rules named once, a divider's
  and a line's 0.1pt rule, borders Word draws as the page does and strokes of no width not
  named; a separator of no width written at two eighths, in its frame and reaching past a
  margin it ends at (the margin written negative), a 20pt one named once though written into
  two headers, a translucent 20pt one named for both, one below zero and one NaN not written,
  named once, and one not written reaching nothing.
• 20 sabotages, each undoing one part — each note, the table's collection, the zero-width
  separator, its frame and its reach, the below-zero and NaN notes, once per band and per
  panel, both thresholds, held widths, the clamp, strokes of no width — all caught.
• Corpus: 62/62 DOCX byte-identical; report notes 1244 → 1246, the two CompactMono header
  rules (CV and cover letter).
• ./mvnw -B -ntp clean verify — BUILD SUCCESS (core 821, render-docx 1736, examples 93,
  qa 1820); the knowledge pack's --check passes.

Lane: render-docx (semantic backend) — report notes and a separator of no width; no layout
change.