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# Data references

An array of data references.

## Overview

Each data reference is formatted like an atom and contains the following data elements.

- Size: A 32-bit integer that specifies the number of bytes in the data reference.
- Type: A 32-bit integer that specifies the type of the data in the data reference. The table below lists valid data reference type values.
- Version: A 1-byte specification of the version of the data reference.
- Flags: A 3-byte space for data reference flags. There is one defined flag, `Self reference`, which indicates that the media’s data is in the same file as the movie atom. On the Macintosh, and other file systems with multi-fork files, set this flag to `1` even if the data resides in a different fork from the movie atom. This flag’s value is `0x0001`.
- Data: The data reference information.

The currently defined data reference types that can be stored in a header atom are as follows:

|Data reference type|Description                                                                                                                                                                                                                                                                                                                                                                                 |
|-------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|`'alis'`           |Data reference is a Macintosh alias. An alias contains information about the file it refers to, including its full path name.                                                                                                                                                                                                                                                               |
|`'rsrc'`           |Data reference is a Macintosh alias. Appended to the end of the alias is the resource type (stored as a 32-bit integer) and ID (stored as a 16-bit signed integer) to use within the specified file. This data reference type is deprecated in the QuickTime file format. This information documents existing content containing `'rsrc'` data references; don’t use it for new development.|
|`'url '`           |A C string that specifies a URL. There may be additional data after the C string.                                                                                                                                                                                                                                                                                                           |

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