Reference Formats
DOC
DOC is Microsoft Word's original binary document format, dating to Word for DOS in 1983 and restructured into the OLE/Compound-File-based version used from Word 97 (1997) through Word 2003.
Extension
.doc
Full name
Microsoft Word Binary File Format
Introduced
1983
Vendor
Microsoft
What is inside the container
The DOC format most commonly encountered today is the Word 97–2003 binary structure — a Compound File Binary (CFB) format, the same general OLE container structure once used by other legacy Office formats, storing text, formatting, and embedded objects as a set of internal binary streams rather than human-readable XML. Unlike DOCX, DOC's binary internals aren't directly inspectable without a parser that understands the compound-file structure, which is why third-party and open-source tools historically had a harder time achieving full DOC compatibility than they later did with DOCX.
How to open it
For archives
DOC should be treated as a migration target, not an archival destination, in a DAM — Microsoft itself has deprecated the format in favor of DOCX, and long-term third-party support for the legacy binary structure is gradually thinning even though Microsoft published the full MS-DOC specification openly in 2008. Legacy .doc files ingested into a DAM should be converted to DOCX (for continued editability) or PDF/A (for immutable archival record) as a standard ingest step, with the original .doc kept only as a reference copy if institutional policy requires preserving the exact bytes originally received.
The .doc extension is older than most people assume — it dates back to Word for DOS in 1983, Microsoft’s first word processor, and remained Word’s native format through many structural changes over the following decade and a half. The version of DOC most DAMs actually encounter today is the one Microsoft restructured for Word 97 in 1997: an OLE/Compound File Binary (CFB) format that stayed Word’s default all the way through Word 2003, before Office 2007 replaced it with the XML-based DOCX.
For most of its life, the binary DOC format was effectively proprietary in practice even though it was never legally secret — reverse-engineering it well enough for full compatibility was hard enough that early open-source office suites struggled with complex DOC documents for years. That changed materially in 2008, when Microsoft published the complete MS-DOC binary specification as part of its broader Open Specification Promise, giving third-party developers an authoritative reference rather than having to infer the format’s internals through trial and error.
| DOC (97–2003) | DOCX | |
|---|---|---|
| Structure | OLE/Compound File Binary | ZIP archive of XML parts |
| Metadata access | Requires a CFB-aware parser | Readable directly from core.xml |
| Format standardized | Published 2008 (Open Specification Promise) | ISO/IEC 29500 (2008) |
| Default since | 1997 (Word 97) | 2007 (Office 2007) |
For a DAM, legacy .doc files are almost always something to migrate away from rather than to keep as the standard working format — Microsoft has deprecated it in favor of DOCX, compatibility tooling continues to thin over time, and the binary structure doesn’t offer the same programmatic transparency DOCX’s ZIP-of-XML design provides. A sound ingest policy converts incoming .doc files to DOCX (if further editing is expected) or PDF/A (if the document is being finalized for the archival record), keeping the original .doc only where an institution’s retention policy specifically requires preserving the exact bytes as received.
Frequently asked
Is the .doc format from Word 6.0/95 the same as the .doc format from Word 97 onward?
No — Microsoft restructured the internal binary format for Word 97 in 1997, and while both use the .doc extension, they're structurally different enough that Microsoft had to release a separate Word 97 Import Converter to let users of the older Word 6.0/95 format open the newer files.
Should a DAM keep ingesting new documents as DOC, or migrate to DOCX?
Migrate to DOCX — Microsoft deprecated DOC in favor of DOCX starting with Office 2007, and DOCX's open, ISO-standardized, XML-based structure offers better long-term tooling support and programmatic transparency than the legacy binary format.
Is Microsoft's binary DOC format publicly documented for third-party DAM tooling to support?
Yes, since 2008 — Microsoft published the complete MS-DOC binary file format specification as part of its Open Specification Promise, giving developers an authoritative reference. Before that, achieving full DOC compatibility required extensive reverse engineering.
Can LibreOffice or Google Docs open old .doc files reliably?
LibreOffice Writer offers strong compatibility, having supported the binary format for years using both reverse-engineered knowledge and, later, Microsoft's published specification. Google Docs converts uploaded .doc files to its own format on import, which usually works well for standard documents but can occasionally alter complex legacy formatting.
Should a DAM convert legacy DOC files to PDF/A or to DOCX?
It depends on intended use — convert to DOCX if the document still needs future editing, and to PDF/A if the document is being finalized as a permanent, unalterable archival record. Many DAM workflows do both: DOCX for the working copy, PDF/A for the compliance record.
Does a legacy .doc file support the same metadata a DOCX file does?
DOC does carry standard document properties (author, title, creation and modification dates, revision count) in its binary structure, but extracting them requires a parser that understands the Compound File Binary format, unlike DOCX where the same metadata sits in a plainly readable XML file inside the ZIP archive.
Can a DOC file contain macros that pose a security risk during DAM ingest?
Yes — the legacy binary format doesn't separate macro-enabled documents into a distinct extension the way DOCX/DOCM does, so any .doc file can potentially carry VBA macros. DAM ingest security scanning should treat all incoming .doc files as potentially macro-bearing regardless of what the filename suggests.
Is there a risk that DOC files become unreadable in the future as software support fades?
It's a real long-term concern — while the format is publicly documented, mainstream application support for the legacy binary structure has been gradually deprioritized since DOCX became the default in 2007, which is exactly why proactive migration rather than passive retention is the recommended DAM practice for any DOC files still in circulation.
Sources
- Microsoft restructured the Word binary file format for Word 97 in 1997 into an OLE/Compound File Binary-based structure that remained the default through Word 2003, before Office 2007 replaced it with DOCX. checked 2026-08-07 — Library of Congress — Microsoft Office Word 97-2003 Binary File Format (.doc)
- Microsoft published the complete MS-DOC binary file format specification publicly as part of its Open Specification Promise. checked 2026-08-07 — Microsoft Learn — [MS-DOC]: Word (.doc) Binary File Format