Limitations

This is the single place that lists what the package does not support. The README intentionally does not repeat it. This is a codec library, not a complete legacy Office renderer, and format detection alone does not imply that content is parsed or editable.

General rules:

• An unsupported edit throws UnsupportedOle2EditError from the document model, or returns the original bytes / a rejected or unchanged status from the lower-level functions. Check the result before reporting success.
• Capabilities describe an editing surface, not the eligibility of every target; a specific cell, shape or paragraph can still be refused.
• Processing is bounded by input, decoded-size, depth and record budgets. Input beyond a budget is refused rather than partially processed.
• Internal Office record offsets are not repaired by container-level stream edits.

For the per-format coverage table and the validation behind it, see Format coverage.

CFB containers

• Supported resize layouts: v3 containers with 512-byte sectors and at most 109 header-listed FAT sectors, and v4 regular streams with 4096-byte sectors.
• Reading accepts only irregularities that cannot change stream bytes; see CFB compatibility. In-place edits refuse irregular containers until they are rebuilt with repairCompoundFile.
• In-place edits cannot create entries; adding, deleting or moving entries requires a full rebuild with buildCompoundFile, which writes v3 only.
• Not supported in place: creating new storage entries, external DIFAT expansion, variable-length v4 mini-stream edits and v4 mini/regular transitions, and high 64-bit stream sizes.
• Allocations are appended, so shrinking a stream does not compact the file.
• Only existing SummaryInformation text properties can be edited, and only when the value fits its slot. Creating or expanding properties and full property-set models are not supported.

See CFB v4 preservation for the tested and refused scenarios.

Word (DOC)

• Only main-body paragraphs and a bounded direct-formatting slice (bold, italic, font size, underline, paragraph alignment) are modeled.
• No style resolution and no new formatting records.
• No paragraph insertion or removal and no embedded paragraph breaks.
• Edits inside field code or result ranges and other CP-dependent structures are refused; tables, objects and other stories have no editable model.
• Mirrored alignment admits only direction-independent center and justify.
• There is no fresh-document writer.

Excel (XLS)

• BIFF8 only; BIFF5 and earlier throw unsupported-version.
• Formulas are never evaluated or written. Cached results are retained and recalculationRequired signals that the consuming application must recalculate.
• No creation of missing cells, no edits to merged followers, and no string-to-BOOLERR conversion.
• Records and layouts with unsafe pointer relocation are refused atomically.
• A selected rich string becomes plain text while other shared aliases keep their formatting.
• Charts, pictures, drawings, conditional formatting, data validation, pivot tables and VBA are listed as unsupported rather than decoded. There is no fresh-workbook writer.

PowerPoint (PPT)

• Text edits keep the UTF-16 length, original encoding and control/field marker positions; arbitrary growth is not supported.
• Slides with an OOXML metroBlob mirror, and physical text atoms shared by several active slide positions, are refused.
• Shape geometry edits cover only unmirrored top-level small-anchor rectangles and text boxes. Shared, grouped, inherited, rotated or flipped geometry is refused.
• Direct character runs are read-only apart from existing inline text-box font sizes; there is no style insertion, run splitting or inheritance resolution.
• Notes fields, rich-run changes and note creation are refused. Outline-to-shape text references can stay unresolved, and group/child coordinates remain local.
• Encrypted files cannot produce a model.
• salvagePptText is read-only and best-effort; its record-scan mode can include text from superseded saves.
• Layout, masters, pictures and animations are not decoded into an editable presentation model.

PPT export

• Several slide masters are written following [MS-PPT] but the consecutive ids for masters after the first have not been verified by reopening in PowerPoint. The first id is verified for single-master decks.
• Picture formats are png, jpg, emf, wmf and dib. GIF, TIFF and SVG sources must be converted by the caller first.
• Media: embedded sound is written as a playable WAV. The model has no video record, so video and non-WAV audio should be passed as their poster picture.
• Encryption uses RC4 CryptoAPI only; the pre-CryptoAPI Office 95 scheme is not written.
• Modern-only content: charts, SmartArt, ink and 3D models have no binary record of their own. Callers write a preview picture and can attach the element's OOXML as a metroBlob so PowerPoint 2007+ reopens it as the native object.

Visio (VSD)

• Binary version 11 only. Earlier versions are not decoded.
• Pages, shapes, stored transforms, UTF-16 text and move/line geometry are read. Styles, masters, general ShapeSheet and formula evaluation, rich text, embedded content, complex geometry and general drawing reconstruction are not.
• Text edits must fit the original allocation and exact decoded length. Insufficient capacity or work budgets refuse.
• Transform edits need an exclusive top-level literal transform with understood unit tags and no parent or master dependency. Literal path points are not rescaled when transform dimensions change.
• Child coordinates remain local and inherited rendering is unresolved.
• Native transform, rendering and complete round-trip parity are unverified. See Visio native validation.

Publisher (PUB)

• Inspection only: known container signatures, versions and required streams.
• Publication pages, text frames, images and layout are not decoded, and there is no writer. Metadata editing is independent of publication content.