# Custom Field Mappings

The ten Custom fields may be mapped to almost any audio container extensible item. In the case of FLAC files, the Custom fields may also be mapped in Preferences - FLAC Mappings.

As a convenience, the display name is displayed and may be modified here.

In ID3 based files Yate supports the mapping of a Custom field to a COMM frame (a comment), a TXXX frame (a UDTI) or a WXXX frame (a UDURL). According to the strict ID3 specification, COMM frames can contain newline characters while TXXX and WXXX frames should not. These frame types are supported so that you can map to any extensible frame used by other applications. The supplied name is the description field associated with the frame. Note: The mapping of a MusicBrainz Recording Id is handled as a special case. While stored in the audio file as a Unique File Identifier it is mapped here as TXXX/MusicBrainz Recording Id.

In m4a/mp4 files Yate supports the mapping of a Custom field to a ---- atom with a mean value of com.apple.iTunes. The name you supply is the name value associated with the atom.

In FLAC files, the following special semantics apply:

- If an empty name is supplied for a mapping, all FLAC mappings assigned to the associated custom field will be removed.
- If the specified name is already mapped to the associated custom field and there is more than one mapping to the field, the specified mapping will be established as the default. (1 button in Preferences - FLAC Mappings)
- If the specified name is used in a FLAC mapping but is not mapped to the associated custom field, all previous uses of the mapping name and all mappings to the associated custom field will be removed prior to creating the new mapping.

If a mapping is set to empty, the associated Custom field will not be read or written.

If you want a custom field to be treated as a credit by the Combined Credits Editor, set the Custom field is a credit option.

Various commonly used mappings may be set via the disclosure button.

The Set Selected Mapping to Default Values will reset only the currently selected custom field. Reset Custom Mapping Defaults will reset all the custom fields.

## Warning:

Changing custom mappings while files are open is extremely dangerous! You will not be allowed to save the changes if any files are open. However, changing FLAC mappings, resetting preferences and importing preferences all potentially change mappings relevant to files that are currently open. Avoid all operations which can alter mappings when files are open.

## Special Consideration:

When loading and saving files Custom Field Mappings are always processed before any normalization occurs of names being saved across multiple audio file types. For that reason you should only map to the names of the low-level file components and not the normalized names which might be used for some user defined items.

The default low level mappings for all Yate supported field types can be found in Yate Field Mapping.