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Section 504 of the Rehabilitation Act of 1973 states that "no qualified individual with a disability in the United States shall be excluded from, denied the benefits of, or be subjected to discrimination under" any program or activity that either receives Federal financial assistance or is conducted by any Executive agency or the United States Postal Service. Each Federal agency has its own set of section 504 regulations that apply to its own programs. Agencies that provide Federal financial assistance also have section 504 regulations covering entities that receive Federal aid. The ADA is based in part on this section of the Rehabilitation Act.


Americans With Disabilities Act. For more information:


Creating a visual display of the program's audio, including spoken words, sound effects “[thunder]” and speaker identification.

Captioning Encoder

Machine that inserts closed caption data into a video.

CART: Stands for Communications Access Realtime Translation

CART reporters typically provide realtime captioning services on site at meetings, events, theater productions and in classrooms. Remote CART is a similar service provided over the internet for conference calls or wired classrooms.

CBC Certification

Certified Broadcast Captioner is a National Court Reporter Association (NCRA) certification that the reporter knows how to work with telecommunications technologies and services.

CCP Certification

Certified CART Provider. CCP is a National Court Reporter Association (NCRA) certification that the reporter can transcribe a meeting or other live session either in person or via conference call, but does not include working with video.


A web browser offered by Google. Available in multiple platforms including Windows and Mac.

Closed Captions

Closed captions are hidden in the video signal and have to be turned on, or "opened" to be seen, while open captions are always visible.


Software and/or hardware that encodes a data stream or signal for transmission, storage or encryption, or decodes it for playback or editing. Media players such as Flash, QuickTime and Windows Media Player as well as the many other “private label” players available have a codec for decoding the data stream. If you want to get really technical:

DFXP (Distribution Format Exchange Profile)

The older name for a captioning format now called Timed Text Markup Language, or TTML. TTML specifies how the captions and timing information are formatted (laid out) for access by the video's player.


“Encoding” can mean different things depending on the context. For example, it can refer to the formatting of a digital video file. In the context of captioning, it refers to the process of marrying close caption data to a video.


An open source web browser produced through the support of the Mozilla Foundation. Available in multiple platforms including Windows and Mac.

Flash (.flv, .fla)

Web video platform developed by Adobe. The user's player is free, and installed on a significant percentage of personal computers. The flash player is available at


Internet Explorer, Microsoft's official web browser. Not available on the Mac. Some web streaming applications, notably for webinars, require the IE browser for effective use.

Live Captions

Another term for realtime captioning.


iTunes video file format. M4V files are used for TV episodes, movies, and music videos in the iTunes Store.

MOV (.mov)

QuickTime video file format.


Moving Pictures Experts Group. Manages standards for compressing video files. The most well known are MPEG-1 through MPEG-4.


A popular video file format for web video.

Progressive download

A process that enables you to watch the video while downloading. Progressive download enables providers to host a video on a web server (as opposed to a specialized streaming server) and emulate a streamed video. Progressive download is recommended only for small video files of extremely short duration.

Offline captions

Common term for captions created for recorded (as opposed to live) media.


Media player for web video and other multimedia files. Commonly associated with the .mov video format. QuickTime players can also play other formats. For a list of supported formats:

Realtime Captioning

Typing captions as the event or program is occurring. When the process includes online display, the captions generally go through an encoder.


Media player for online video. Uses a proprietary video format.

Recorded Captions

Another term for offline captions.

Rehabilitation Act of 1973

Legislation that provides framework for non-discrimination and accessibility-related legislation. For example, the current form of "Section 508" is from a 1998 amendment to the Rehabilitation Act regarding access to electronic and information technology. The ADA is based on language from Section 504 of the Rehabilitation Act.


Browser developed by Apple for the Mac. Also available on other platforms.

SAMI (Synchronized Accessible Media Interchange)

A caption file for use with Windows Media Player. For more information:


File extension used by Sonic Solution's "Scenarist." SCC files are most commonly used by DVD authoring programs.

Section 508

Federal technical standards for accessibility. For more information:


Web video platform developed by Microsoft to compete with Flash.

SMIL (Synchronized Multimedia Integration Language)

W3C-recommended XML markup language that is also a caption file format for videos run in QuickTime and Real Player environments. W3C on SMIL: Adding SMIL to QuickTime:

SRT (.srt)

SubRip, a caption file format supported by YouTube.

Streaming Media

Method of delivering media, typically video, over internet that enables constant presentation to end user, as opposed to a download. Streaming media typically uses specialized resources such as a streaming server and related technologies.

SUB (.sub)

SubViewer, a caption file format supported by YouTube.


Typically used to describe foreign language captions which are always visible, as opposed to closed captions, which can be turned on and off. However, in DVDs and even internet video, users may have the ability to choose to turn on a particular subtitle file. For example, see videos at – most (but not all) offer subtitles in a variety of languages.

Timed Text Markup Language (TTML or TT XML)

Captioning format specified by the W3C that specifies how the captions and timing information are formatted (laid out) for access by the video's player. The goal was to set up a standard that all players would follow. As it is, you have to use specific formats for specific players. A number of players do support TT (also called DFXP), including Flash, and YouTube. The W3 TTML standard is located at


Verbatim text of a program's audio. A clean transcript can facilitate efficient captioning. In addition, a transcript may be used with automatic timing tools where precise timing is not required.


The technology and practice of using specialized hardware and software to enable a trained individual to speak into a microphone to generate text output. Typically the voicewriter speaks into a specialized  microphone called a steno mask.


A codec specification best known for use by Flash media players.


The acronym for the international standards group World Wide Web Consortium. Nearly all general internet standards are subgroups formed under the W3C umbrella. Learn more at

WCAG 2.0 (Web Content Accessibility Guidelines)

WCAG is the Web Accessibility Initiative standards group under the auspices of the W3C. Learn more at

Windows Media Player (.wmp)

Microsoft's video player for Windows computers. While it can run many different video formats, it's native format is wmp. Mac users can either use Flip4Mac, a QuickTime plug-in, or other player converter software to run wmp files. For more information:

XML (Extensible Markup Language)

XML is a set of rules for encoding documents in machine-readable form. For example, HTML is another set of rules for encoding documents that is commonly used to format text pages for web browsers. However, XML has far broader applications, of which caption file formats is just one.

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