.DOC

Word binary document

Introduction

.doc is the extension of Microsoft Word’s binary documents, the default format until Word 2007 replaced it with DOCX. Billions of these files still exist, and every current word processor can open them.

The format changed several times. Word for Windows 1.x and 2.0 wrote a plain binary file. Word 6.0 (1993) and Word 95 moved the document into a compound file, a small file system inside the file. Word 97 kept the compound file but changed the document inside it, adding Unicode text, and Word 2000, 2002 and 2003 kept the Word 97 format. Word for MS-DOS and early versions of Word for the Mac also used .doc for formats of their own.

Variations

FormatVariationAboutOpen
.DOCWord 6.0 and 95 documentWord 6.0 and 95 documents: single-byte text in one compound file stream.Open
.DOCWord 97–2003 documentWord’s binary document from Word 97 to 2003: streams in a compound file.Open

Word 6.0 and 95

The format of Word 6.0 and Word 95 (Word 7). Text is stored in single-byte characters of a Windows code page, and all of the document, its text, formatting and tables, is in one stream.

The file is a compound file holding a WordDocument stream, which starts with the File Information Block. Its first two bytes, wIdent, are 0xA5DC, and nFib is 101 for Word 6.0 or 104 for Word 95. There is no 0Table or 1Table stream.

Word 97 to 2003

The format of Word 97, 2000, 2002 and 2003, and the one most .doc files use. Text can be Unicode, and the tables that describe the document, such as the piece table, styles and fonts, move to a separate table stream.

The WordDocument stream starts with a File Information Block whose wIdent is 0xA5EC and whose nFib is 193 (0x00C1). The compound file also holds a table stream named 0Table or 1Table.

Links

Software

Developers

  • Apache POI, Java library for Office files, Word documents through its HWPF classes

Reference