Rich Text Format

Rich Text Format. Rich Text Format is a proprietary document file format developed by Microsoft in 1987 to facilitate cross-platform document interchange. It encodes formatted text and graphics for transfer between different word processor applications and operating systems. While largely succeeded by modern formats like Office Open XML, it remains a widely supported standard for basic document sharing.

History

The format was created by the Microsoft Word team, notably programmer Charles Simonyi, to serve as a default interchange format for its Microsoft Word application. Its development was concurrent with the rise of competing word processors like WordPerfect and the need for a common format that could preserve basic formatting across different software on systems like Classic Mac OS and early versions of Microsoft Windows. The specification was publicly documented, allowing other companies, including Lotus Software and Corel, to implement support in their products like Lotus 1-2-3 and WordPerfect Office. Major revisions were released throughout the 1990s, with version 1.0 standardized in 1993 and later versions adding support for elements like Unicode and the Object Linking and Embedding framework. The format's role diminished with the introduction of XML-based standards, but it saw a resurgence in the early 2000s as a safer alternative to Microsoft Word's native .doc format for mitigating macro virus threats.

Technical details

At its core, the format uses a markup language syntax composed of control words, symbols, and groups delineated by braces. This plain-text approach allows it to be human-readable and editable with basic tools like the Windows Notepad application. It specifies commands for character formatting such as font family, font size, and styles like bold and italic, as well as paragraph formatting including indentation, tab stops, and text alignment. The format can encapsulate Metafile graphics, JPEG and PNG images, and objects from other applications via the OLE protocol. Support for complex typography includes footnotes, endnotes, bookmarks, and basic table (information) structures. Its encoding historically relied on ASCII or code pages, but modern implementations use Unicode via the UTF-8 and UTF-16 encoding schemes to represent a global character set.

File format

A file is identified by the filename extension `.rtf` and typically begins with the header `{\rtf1` followed by a character set declaration. The body contains a sequence of control groups defining the document's content, stylesheets, fonts, color tables, and embedded data. Graphics are stored in hexadecimal format or as Windows Metafile or Enhanced Metafile blobs. The structure is hierarchical, with formatting properties scoped within brace-delimited groups, allowing for nested elements. While the specification is published by Microsoft, the format's interoperability has been aided by reverse-engineering efforts and its adoption in open-source projects like LibreOffice and the Apache OpenOffice suite. Files can be compressed using the PKZIP algorithm, resulting in a .rtf.zip file, though this is not universally supported.

Usage and applications

Its primary historical use was for exchanging documents between different word processors, such as from Microsoft Word to Apple Pages or OpenOffice.org. It became a common format for technical documentation, software manuals, and résumés due to its wide support. Many email client applications, including Microsoft Outlook and Mozilla Thunderbird, can send and receive messages formatted in it. The format is also frequently used as an export and import filter in desktop publishing software like Adobe FrameMaker and QuarkXPress. In legal and academic contexts, it served as a stable format for submitting documents to systems like the United States Courts Case Management/Electronic Case Files system before the adoption of the Portable Document Format. Its simplicity made it a popular output format for early help authoring tools and text editors on platforms like IBM OS/2 and BeOS.

Related formats

The format is a direct precursor to the Microsoft Word .doc and .docx (Office Open XML) formats, which offer greater feature complexity. The OpenDocument standard, developed by the Organization for the Advancement of Structured Information Standards and used in LibreOffice, provides similar cross-platform functionality with an open specification. Simpler plain text alternatives include TXT files and the TeX typesetting system, while more advanced interchange formats include the Portable Document Format from Adobe Inc. and the HyperText Markup Language used for the World Wide Web. Other proprietary formats with rich text capabilities include Apple's Apple Mail .eml format and the WordPerfect .wpd document format.

Category:Document file formats Category:Microsoft file formats Category:Text-based data formats