---
title: "Metadata key declaration atom ('keyd')"
framework: quicktime-file-format
role: symbol
role_heading: Atom
path: quicktime-file-format/metadata_key_declaration_atom
---

# Metadata key declaration atom ('keyd')

An atom that holds the key namespace and key value of that namespace for the given values.

## Overview

Overview The metadata key declaration atom holds the key namespace and key value of that namespace for the given values. The type of the metadata key declaration atom is ‘keyd’. The layout of a metadata key declaration atom is as follows:  |   |   |   |   |

## Topics

### Data fields

- [Size](quicktime-file-format/metadata_key_declaration_atom/size.md)
- [Type](quicktime-file-format/metadata_key_declaration_atom/type.md)
- [Key_namespace](quicktime-file-format/metadata_key_declaration_atom/key_namespace.md)
- [Key_value array](quicktime-file-format/metadata_key_declaration_atom/key_value_array.md)

## See Also

### Describing timed metadata

- [Metadata key table atom ('keys')](quicktime-file-format/metadata_key_table_atom.md)
- [Bit rate atom ('btrt')](quicktime-file-format/bit_rate_atom.md)
- [Metadata key atom](quicktime-file-format/metadata_key_atom.md)
- [Metadata datatype definition atom ('dtyp')](quicktime-file-format/metadata_datatype_definition_atom.md)
- [Metadata locale atom ('loca')](quicktime-file-format/metadata_locale_atom.md)