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Captioning Key - Language Mechanics

  1. Spelling and Capitalization
  2. Punctuation and Grammar
Language mechanics incorporate the proper use of spelling, capitalization, punctuation, grammar, and other factors deemed necessary for high-quality captioned media. Rules included in these guidelines are primarily those which are unique to captioning and speech-to-text. For conventional words, dictionaries and style guides must be followed. Proper names, technical terms, and specialized language must be verified though specialty references or directly from an authoritative source.

Spelling and Capitalization

  • Do not emphasize a word using all capital letters except to indicate screaming or shouting.
  • Be consistent in the spelling of words throughout the media. This includes vocabulary that can be spelled either as one or two words or in hyphenated form.
  • Capitalize proper nouns for speaker identification. All other speaker identification should be lowercased unless this identification is being used as a proper noun.
  • Lowercase sound effects, including both description and onomatopoeia, except when a proper noun is part of the description.
  • See the Numbers section on the Captioning Key Appendices page for detailed guidelines for numbers including dates, time, periods of time, fractions, percents, dollar amounts, and measurements.

Punctuation and Grammar


  • When captioning a list separated by commas, use a serial, or Oxford, comma. Example:


    I'm having eggs, bacon and toast.


    I'm having eggs, bacon, and toast.

Hyphens and Dashes

  • When a speaker hesitates or stutters, caption what is said.

    Correct Example

  • When captioning spelling (including fingerspelling), separate capital letters with hyphens.

    Correct Example



  • Use an ellipsis when there is a significant pause within a caption.
  • Do not use an ellipsis to indicate that the sentence continues into the next caption.
  • Use an ellipsis to lead into or out of audio relating to an onscreen graphic.
    Video still says 130 million of the world's youth are not attending school. Caption reads '...70% are girls.'
    Video still says 130 million of the world's youth are not attending school. Caption reads '...70% are girls.'

Quotation Marks

  • Use quotation marks for onscreen readings from a poem, book, play, journal, or letter. However, use quotation marks and italics for offscreen readings or voice-overs.
  • Beginning quotation marks should be used for each caption of quoted material except for the last caption. The last caption should have only the ending quotation mark.

    Correct Example

    Reading from a journal…

    "Mother knelt down
    and began thoughtfully fitting

    "the ragged edges
    of paper together.

    The process was watched
    with spellbound interest."


  • Spaces should not be inserted before ending punctuation, after opening and before closing parentheses and brackets, before and after double hyphens and dashes, or before/between/after the periods of an ellipsis.
  • A space should be inserted after the beginning music icon (♪) and before the ending music icon(s).

    Correct Example

    ♪ There's a bad moon rising ♪


Use italics as follows:

  • A voice-over reading of a poem, book, play, journal, letter, etc. (This is also quoted material, so quotation marks are also needed.)
  • When a person is dreaming, thinking, or reminiscing.
  • When there is background audio that is essential to the plot, such as a PA system or TV.
  • The first time a new word is being defined, but do not italicize the word thereafter.
  • Offscreen dialogue, narrator (see Exception 2 below), sound effects, or music (this includes background music).
  • The offscreen narrator when there are multiple speakers onscreen or offscreen.
  • Speaker identification when the captioned dialogue is in italics.
  • Foreign words and phrases, unless they are in an English dictionary.
  • When a particular word is heavily emphasized in speech.

    Correct Example

    You must go!

Exceptions to the use of italics include:

  • When an entire caption is already in italicized format, use Roman type to set off a word that would normally be italicized.
  • If there is only one person speaking throughout the program (including the narrator), whether onscreen or offscreen, use Roman type with no italics.
  • Do not italicize when a person who is offscreen is translating for a speaker who is onscreen.
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