6.4 KiB
6.4 KiB
File-format parity
Last reviewed: 2026-10-10 · Last updated: 2026-10-10 · Change: major (created; every format Excel reads or writes, against the code on main) · Target: Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
Every format Excel opens or saves, with GridCraft's read and write support, fidelity and tests. Part of target-app-parity.md. File formats: ~50% ready, 80–120 h (estimated).
Excel's list comes from Microsoft's public "File formats that are supported in Excel"
documentation (the Office bundle is off limits under this repo's clean-room rule). GridCraft's
support comes from crates/engine/src/io.rs (FileKind), crates/xlsx/src and the tests in
crates/xlsx/src/tests/ (round-trip, fixtures, malformed input, CSV, ODS, XLSB, PivotTables).
Workbook formats
| Format | Excel | GridCraft read | GridCraft write | Fidelity / notes | Tests |
|---|---|---|---|---|---|
.xlsx Excel Workbook (transitional) |
R/W, native | yes | yes | Cells, shared/array/dynamic formulas, styles, themes, merges, CF, validation, tables, comments and notes, hyperlinks, names, freeze panes, outline, print settings, pictures, shapes, charts (simplified, see chart-parity.md), sparklines, PivotTables (caches and tables), protection, calc settings. Not preserved: unmodelled parts and extensions (form controls, slicer caches, timelines, external links, OLE objects, custom XML, data model, query tables, chart details). Never checked in Excel across a corpus: repair prompts unknown. 100 MB files fail (#175) | roundtrip.rs, fixtures.rs, malformed.rs, pivot_tests.rs |
.xlsx Strict Open XML |
R/W | yes | no (writes transitional) | Excel also saves transitional by default | fixtures |
.xlsm Macro-Enabled Workbook |
R/W | yes | yes, without macros | VBA project dropped with a warning; saving as .xlsm loses the macros (#6) |
— |
.xltx / .xltm templates |
R/W | yes | partial | Saved with the workbook content type, not the template one; "new from template" behaviour missing | — |
.xlsb Binary Workbook |
R/W | values only (#101) | no | Names, visibility, numbers, text, booleans, errors, merges, cached formula results; no formulas, formatting, charts, names | xlsb_tests.rs |
.xls Excel 97-2003 (BIFF8) |
R/W | no (#121); recognised and refused with a message since #17 | no | Still common in finance, government and legacy systems | — |
.xlt Excel 97-2003 template |
R/W | no | no | — | |
.xlam / .xla add-ins |
R/W | no | no | VBA; out of scope | — |
.xml XML Spreadsheet 2003 |
R/W | no | no | Simple to support | — |
.ods OpenDocument Spreadsheet |
R/W | values only (#100) | no | Sheets, values, dates, merges, repeated cells, cached formula results; no formulas, formatting, charts; encrypted ODS refused | ods_tests.rs |
| Password-encrypted workbooks (Agile/Standard encryption) | R/W | no; recognised and refused with a clear message since #17 | no | Common in business; needs AES decryption on top of the new CFB reader (crates/xlsx/src/cfb.rs) |
— |
.xlw Excel 4.0 workbook, .wk*, .dbf |
open only (some) | no | no | Rare | — |
Text and data formats
| Format | Excel | GridCraft read | GridCraft write | Notes |
|---|---|---|---|---|
.csv UTF-8 / Windows / Mac / MS-DOS |
R/W | yes (UTF-8 and UTF-16 BOMs, UTF-8, Windows-1252 fallback; delimiter detection) | yes (UTF-8 without BOM, CRLF) | Excel writes the displayed values; we write raw values. No encoding choice on save. Re-import of a single-column export splits text (#127) |
.txt tab-delimited, Unicode text |
R/W | yes (.txt, .tsv, .tab) |
yes | Text Import Wizard options partly via Text to Columns |
.prn formatted text (space-delimited) |
R/W | no | no | |
.dif, .slk (SYLK) |
R/W | no | no | Small, legacy |
.htm / .html web page |
R/W (Windows) | yes, via Get Data ▸ From HTML | yes (one sheet as a table) | Formatting not exported |
.mht / .mhtml single-file web page |
R/W (Windows) | no | no | |
.json |
via Power Query | GridCraft's own workbook JSON (debug) and JSON import | GridCraft JSON | Not Power Query's JSON shaping; notes and hyperlinks break export (#126) |
.xml with XML maps |
Developer ▸ Import/Export | no | no |
Export and print
| Format | Excel | GridCraft | Notes |
|---|---|---|---|
| Save As / Export | yes (own PDF 1.7 writer) | Only the 14 standard PDF fonts, no embedding: non-Latin text (CJK, Arabic, Devanagari, Thai) does not export; web build exports without a file prompt (#141) | |
| XPS | Windows | no | Low priority |
| yes | yes (via PDF, system dialog on desktop; PR #143 for web) | ||
| Images of ranges/charts (Copy as Picture) | yes | chart raster in crates/chart |
No range-to-image command |
Import sources (Get & Transform)
Excel's Get Data reaches files (Excel, CSV, XML, JSON, PDF, Parquet, folders), databases (SQL Server, Access, ODBC, …), web pages, SharePoint and online services, through Power Query. GridCraft imports CSV/TSV, JSON and HTML tables only, with no query editor, no connections and no refresh. Counted under features (Get & Transform, ~10% ready), not here.
Work (80–120 h)
| Work | Hours |
|---|---|
| Real-world XLSX corpus run (craftrules test-corpora standard), and confirm Excel opens our output with no repair prompt (owner runs Excel) | 15–25 |
| Preserve unmodelled XLSX parts and extensions on round trip (pass-through with relationship fix-up) | 10–15 |
| Streaming XLSX reader for very large files (#175), part-size limits that degrade instead of failing | 10–15 |
Legacy .xls (BIFF8) import: cells, formulas, styles, names; then write |
20–30 |
| Encrypted workbooks: open with password prompt, save with password (#11) | 8–12 |
| XLSB and ODS: formulas and formatting on import; then write | 10–15 |
CSV/text: displayed-value export, encoding choice, .prn, .dif, .slk, XML Spreadsheet 2003 |
5–8 |
| PDF: embed subsetted system fonts so every script exports | (counted in localization script work) |
Revision history
| Date | Change | Summary |
|---|---|---|
| 2026-10-10 | minor | Encrypted and .xls files are now recognised and refused with a message (#17) |
| 2026-10-10 | major | Created: every Excel format with our read/write support; XLSB and ODS values-only imports recorded; .xls, encryption and large files flagged as beta gates |