wordcraft/docs/file-format-parity.md

# File-format parity with Microsoft Word

> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-11 · **Change:** trivial (import/export fixes for TXT, RTF, ODT, HTML and LaTeX, #433–#440; previously major: first version; every format Word reads or writes, measured from the readers and writers on origin/main) · **Target:** Microsoft Word (Microsoft 365) for Mac 16.113.4, plus Word for Windows' extra formats

Every format Word opens or saves, what WordCraft does with it, and how it's tested. Fidelity is the
share of a typical real-world file's content and formatting that survives (read: shows correctly;
write: Word opens it showing the same). Summary in [`target-app-parity.md`](target-app-parity.md);
the work items are in [`gaps.md`](gaps.md).

**Dimension: ~60% (estimated), 185–300 h to full** (the sum of the rows below). The weighted table
gives ~64%; we discount it to ~60% because DOCX fidelity has never been checked on real-world
files. DOCX dominates the weight: a Word user sends and receives .docx; everything else is
occasional.

## Formats

Weights are the share of a Word user's file traffic (estimate). Read/write: ✅ yes, 🟡 partial,
❌ no, — Word doesn't either.

| Format | Weight | Word | WordCraft read | WordCraft write | Fidelity | Hours | How it's tested | Notes |
|---|---|---|---|---|---|---|---|---|
| `.docx` Word Document (ECMA-376 Transitional) | 70% | R/W | ✅ | ✅ | ~65% | 70–110 | `crates/docx/tests` (roundtrip 34, fixtures 29, malformed 8, bidi 5, citations 5); synthetic fixtures only | Word opens our files. Untested on a real-world corpus. Details below |
| `.docx` Strict Open XML | 1% | R/W | ✅ (namespace mapping in `xml.rs`) | ❌ | ~60% | 2–4 | one fixture | Writing Strict is rare |
| `.docm` / `.dotx` / `.dotm` | 3% | R/W | ✅ | ✅ | ~65% | incl. above | `macro_packages.rs` | Macros and signatures kept on save (#172); macros never run |
| `.doc` Word 97-2003 (and `.dot`) | 8% | R/W | 🟡 | ❌ | ~55% | 25–40 | `crates/docbin/src/tests.rs` (56) | Spec-based reader ([MS-DOC]): text, formatting, styles, sections, headers/footers, tables, lists, notes, fields, bookmarks, pictures. Metafile (WMF/EMF) pictures, Word 6/95 files and encrypted files are refused or dropped. No writer |
| PDF export | 8% | W | — | ✅ | ~80% | 6–10 | `crates/pdf/src/tests.rs` | krilla: embedded subsets, selectable text incl. field results (#133), links, outline, tagging. Fonts it can't subset become outlines (#132). No PDF/A option, no "best for printing/online" choice |
| PDF open (PDF Reflow, Word for Windows) | 1% | R | ❌ | — | 0% | 30–50 | — | Converting a PDF into an editable document. A sibling app (PdfCraft) may supply the parser |
| `.rtf` Rich Text Format | 3% | R/W | 🟡 | 🟡 | ~50% | 10–15 | `crates/formats/src/tests.rs` | ~1,500 lines: text, character/paragraph formatting, styles, lists, tables, pictures (`\shppict`, #154), fields, bookmarks. Thin: comments, notes, revisions, sections, RTL |
| `.odt` OpenDocument Text | 2% | R/W | 🟡 | 🟡 | ~50% | 8–12 | `crates/formats/src/tests.rs` | Styles, lists (#87), tables, pictures, headers/footers, page breaks (#86). No footnotes, comments, tracked changes, fields or RTL |
| `.txt` Plain text | 2% | R/W | ✅ | ✅ | ~95% | 1–2 | unit tests | Encoding detection; Word's encoding choice dialog and line-ending options missing |
| `.htm/.html` Web Page and Web Page, Filtered | 1% | R/W | 🟡 | 🟡 | ~60% | 6–10 | `crates/formats/src/tests.rs` | Tables (#102), relative pictures embedded (#113), missing `</head>` tolerated (#154). No Word "Web Page" (with `_files` folder) round-trip |
| `.mht/.mhtml` Single File Web Page | <1% | R/W | ❌ | ❌ | 0% | 3–5 | — | |
| `.xml` Word XML Document (Flat OPC) | <1% | R/W | ❌ | ❌ | 0% | 3–5 | — | The DOCX parts in one XML file; cheap once the DOCX code is reused |
| `.xml` Word 2003 XML (WordprocessingML 2003) | <1% | R/W | ❌ | ❌ | 0% | 5–8 | — | Legacy |
| `.wps` Works 6–9, WordPerfect `.wpd` (Windows) | <1% | R | ❌ | — | 0% | 10–20 | — | Windows-only converters; low value |
| Encrypted/password-protected `.docx`/`.doc` | 1% | R/W | ❌ | ❌ | 0% | 6–10 | — | ECMA-376 Agile Encryption; `.doc` RC4/XOR detected and refused (`docbin` fib). Issue #55 |
| `.xlsx`/`.xlsm`/`.ods` as a mail-merge recipient list | — | R (data source) | ✅ | — | ~90% | 1–3 | `crates/formats/src/sheet.rs`, `cmd/mailings.rs` | Read-only, one sheet's cell values (#334): shared/inline/rich strings, numbers, booleans, cached formula results, dates and times as ISO 8601 (`yyyy-mm-dd`) from the cell's number format, sparse cells; ODS value types, repeated rows/columns, covered cells. Select Table picks the sheet. Capped (64 MiB per part, 100,000 rows, 1,000 columns, 2 M cells, 32,767 characters a cell). Not shown: number formats other than dates (currency, percent, thousands separators) in `.xlsx`; no `.xls`, Access or Outlook sources |
| `.md` Markdown | — | (no) | ✅ | ✅ | — | — | `crates/formats/src/tests.rs` | Beyond Word |
| `.tex` LaTeX | — | — | ✅ | ✅ | — | — | `crates/formats/src/tests.rs` | Beyond Word (#11), incl. math |
| `.png` page images | — | (Save as picture, Mac) | — | ✅ | — | — | `io_ext.rs` | |
| `.json` document model | — | — | ✅ | ✅ | — | — | engine tests | For agents |

## DOCX in depth

Measured by grepping `crates/docx/src/read` and `src/write` for the OOXML elements (2026-10-10).

| Feature | Read | Write | Notes |
|---|---|---|---|
| Text, runs, paragraph and character properties, styles, numbering, sections | ✅ | ✅ | Including complex-script props (`w:rtl`, `w:cs`, `w:szCs`, `w:bCs`…), East Asian fonts kept apart from Latin (#111) |
| Tables incl. floating (`w:tblpPr`), table styles and conditional formatting | ✅ | ✅ | Custom table styles round-trip (#256); right-to-left tables (`w:bidiVisual`) and sections (`w:bidi`) round-trip (#362) |
| Headers/footers (first, even/odd), page borders, line numbers, gutter, mirror margins | ✅ | ✅ | |
| Footnotes, endnotes, comments | ✅ | ✅ | The document's own note separators and continuation notice (`w:type` `separator`, `continuationSeparator`, `continuationNotice`) round-trip as ids -1, 0 and 1 (#352); note options (`w:pos`, `w:numFmt`, `w:numStart`, `w:numRestart`) round-trip in the settings and in each `w:sectPr` (#385); `commentsExtended` written; `commentsIds`, modern threaded comments (`w16cex`) partly |
| Tracked insertions and deletions (`w:ins`/`w:del`), paragraph-mark revisions | ✅ | ✅ | #125, #244 |
| Formatting revisions (`w:rPrChange`, `w:pPrChange`, `w:sectPrChange`, `w:tblPrChange`, `w:trPrChange`, `w:tcPrChange`, `w:numberingChange`) | ✅ | ✅ | #41: kept on open and save, schema order (change element last); changes inside `styles.xml` are dropped. RTF/ODT ignore them |
| Move tracking (`w:moveFrom`/`w:moveTo`) | 🟡 | ❌ | Read as plain insert/delete |
| Fields (`w:fldChar`, `w:fldSimple`), TOC, cross-references, `ADDIN` citations | ✅ | ✅ | Field codes Word supports but we don't evaluate keep their cached result. `EQ \o` (overstrike, enclosed characters) is drawn; enclosed characters are written as Word stores them, their style in the code's run sizes (#297) |
| Content controls (`w:sdt`) | 🟡 | ❌ | Content kept, the control (type, binding, placeholder, lock) dropped |
| Legacy form fields (`w:ffData`), check boxes, drop-downs | ❌ | ❌ | |
| DrawingML pictures inline and anchored (`wp:anchor`), wrap square/tight/through/top-bottom | ✅ | ✅ | Tight/through read and written with their `wp:wrapPolygon` (and `edited`); without one, a shape's outline is written (a picture's rectangle). `wrapText` (both sides, left, right, largest) read and written for square, tight and through |
| DrawingML shapes and text boxes (`wps:`) | ✅ | ✅ | Preset geometries subset; rotation and flips (`a:xfrm` `rot`/`flipH`/`flipV`, pictures and groups too, #332), the effect extent covering the rotated bounds; `wps:bodyPr` `vert` and `anchor`, linked text boxes (`wps:txbx/@id`, `wps:linkedTxbx` `id`/`seq`, #369) |
| Freeform shapes (`a:custGeom`: `a:moveTo`, `a:lnTo`, Bézier curves flattened) and WordCraft ink | ✅ | ✅ | Ink is written as a freeform `wps:wsp` in a `wp:anchor` (round caps, alpha for highlighter) and recognised again by its drawing name (#307). It is saved as a custom-geometry shape, not as Word's own ink (InkML in `w14:contentPart`), so Word shows WordCraft ink as a freeform shape it can move and recolour but not erase with its ink eraser; arcs drawn straight |
| Group shapes (`wpg:`), drawing canvas (`wpc:`) | ✅ | ✅ | Groups (#267) and canvases (#344) with pictures, shapes and text boxes; nested groups flattened. The canvas schema has no transform, so a turned or flipped canvas keeps its turn in our own `wpc:extLst` extension (`urn:wordcraft:canvas-xfrm`; Word shows it unturned). Legacy VML canvases (`v:group editas="canvas"`) aren't read as canvases |
| VML (`w:pict`, `v:shape`, `v:textbox`) | 🟡 | ❌ | Pictures and text boxes, best effort (#242) |
| Charts (`c:chart`), SmartArt (`dgm`) | ✅ | ✅ | Drawn from the chart's cached data and SmartArt's stored drawing (#292); not editable. Saved back as read, with every part they reach (chart, embedded workbook, colours and style; diagram data, layout, quick style, colours and drawing) and their content types; a moved or resized one keeps its new frame, and a pasted copy gets its own parts (#319) |
| OLE objects (`w:object`: embedded or linked files, ActiveX) | 🟡 | ✅ | Shown as their picture (VML or DrawingML); saved back whole with the embedding and picture parts, at the size, rotation and flips set in WordCraft (#319, #332). Can't be opened or edited |
| Word ink (`w14:contentPart`, InkML), 3D models | ❌ | ❌ | Dropped on read, not preserved on save |
| Equations (OMML `m:oMath`) | ✅ | ✅ | #191; manual breaks (`m:brk`) and the settings' `m:mathPr` wrapping options (#326) |
| Themes, font table, settings, compatibility mode | ✅ | ✅ | Embedded fonts (`w:embedRegular`) not read |
| Custom XML parts, document properties, bibliography sources | 🟡 | 🟡 | Custom properties round-trip; bibliography sources pending (#169) |
| Ruby (`w:ruby`: `w:rubyPr`, `w:rt`, `w:rubyBase`) | ✅ | ✅ | #288; base and ruby text with their run formatting, alignment, sizes, raise, language |
| `w:eastAsianLayout`, `w:fitText`, document grid (`w:docGrid`) | ❌ | ❌ | East Asian layout |
| Glossary document (building blocks), `w:altChunk`, sub-documents | ❌ | ❌ | |
| Hostile input | ✅ | — | `malformed.rs`, capped allocations, never-crash standard |

## What decides beta for formats

1. A **real-world DOCX corpus** opened, rendered and round-tripped, compared page by page with
   Word (local only: Word output can't be committed; keep a manifest and our own renders).
2. **Preserve what we can't render**: ink, group shapes and content controls survive a round trip
   (keep the parts and the run). Charts, SmartArt and OLE objects do (#292, #319).
3. Formatting revisions and content controls read and written.
4. Encrypted `.docx` opens with a password.

## Revision history

| Date | Change | Summary |
|---|---|---|
| 2026-10-11 | trivial | DOCX text-box `bodyPr` `vert`/`anchor` and linked text boxes (`wps:linkedTxbx`) read and written (#369) |
| 2026-10-10 | trivial | Right-to-left tables (`w:bidiVisual`) read and written (#362) |
| 2026-10-10 | trivial | Drawing canvas (`wpc:wpc`) read and written (#344); group shapes row brought up to date (#267) |
| 2026-10-11 | trivial | Spreadsheets (.xlsx/.xlsm/.ods) read as mail-merge recipient lists (#334) |
| 2026-10-11 | trivial | Import/export fixes (#433–#440): TXT opens through the encoding-sniffing reader (Windows-1252, unmarked UTF-16) and saves list labels; RTF `\uN` in document info, bookmark names and field instructions; ODT common paragraph styles' text formatting and table-cell background colours; HTML borderless tables export without cell borders and `white-space:pre` keeps edge spaces; LaTeX brace groups scope `\centering`/`\raggedleft`/`\raggedright` |
| 2026-10-11 | trivial | `.doc` import fixes per [MS-DOC]: piece Prm0/Prm1 decoding (#458), section-break kinds (#459), explicit orientation (#460), negative `sprmPIlfo` list references (#461), zero-based `istdBase` style inheritance (#462), font-table entries with alternate names (#463) |
| 2026-10-11 | trivial | Formatting revisions (`w:rPrChange`, `w:pPrChange`, table, row, cell, section and numbering changes) read and written (#41) |
| 2026-10-10 | trivial | OLE objects turned or flipped in WordCraft keep the turn on save (VML `rotation`/`flip`, DrawingML `a:xfrm` with the rotated effect extent); test counts refreshed |
| 2026-10-10 | trivial | Charts, SmartArt and OLE objects written back on save with their parts (#319); chart/SmartArt reading (#292) recorded |
| 2026-10-10 | trivial | Footnote and endnote separators and continuation notices read and written (#352) |
| 2026-10-11 | trivial | Enclosed characters (`EQ \o\ac`) read, drawn and written (#297) |
| 2026-10-11 | trivial | Ruby (`w:ruby`) read and written (#288) |
| 2026-10-10 | trivial | `wrapText` on square, tight and through wraps read and written (#354) |
| 2026-10-10 | trivial | Wrap polygons for Tight and Through wrapping read and written (#354) |
| 2026-10-10 | trivial | DrawingML rotation and flips read and written (#332) |
| 2026-10-11 | trivial | Footnote and endnote options round-trip for the document and per section (#385) |
| 2026-10-10 | trivial | Equation breaks and `m:mathPr` wrapping options round-trip (#326) |
| 2026-10-10 | trivial | Custom table styles round-trip (#256 merged) |
| 2026-10-10 | major | First version: Word's full format list, read/write status, DOCX element coverage from the source, fidelity and hours |
| 2026-10-10 | trivial | Freeform shapes and ink as DrawingML custom geometry, read and written (#307) |