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# Wide atom ('wide')

An atom that designates reserved space in the movie data file.

## Overview

A `wide` atom typically precedes a movie data atom. The `wide` atom consists only of a `type` and `size` field. This occupies 8 bytes—enough space to add an extended size field to the header of the atom that follows, without displacing the contents of that atom. If an atom grows to exceed 2^32 bytes in size, and it is preceded by a `wide` atom, you may create a new atom header containing an extended size field by overwriting the existing atom header and the preceding `wide` atom.

## Topics

### Data fields

[`Size`](/documentation/quicktime-file-format/Wide_atom/Size)

A 32-bit integer that specifies the number of bytes in the atom.

[`Type`](/documentation/quicktime-file-format/Wide_atom/Type)

A 32-bit integer that identifies the atom type.


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