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# Component subtype

A four-character code that identifies the type of the media handler or data handler.

## Overview

For media handlers, this field defines the type of data — for example, `'vide'` for video data, `'soun'` for sound data or `‘subt’` for subtitles. See [Media data atom types](/documentation/QuickTime-File-Format/Media_data_atom_types) for information about defined media data types.

For data handlers, this field defines the data reference type; for example, a component subtype value of `'alis'` identifies a file alias.

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