register
FLAC allows third-party applications to register an ID for use with FLAC APPLICATION metadata blocks. Contact the FLAC-dev mailinglist to register an ID or to change an existing ID. Your request should at least contain the application ID, application name and a contact e-mail address. An application URL and specification URL should be mentioned too, if applicable.
The ID request should be 8 hexadecimal digits and not conflict with any existing IDs (see the table below for all currently registered IDs). This 32-bit number will be stored big-endian in the block.
Information about your application (but not your e-mail address) will show up on this page in the ID directory. You can also provide a URL to your application and a URL reference to the specification of your application's APPLICATION block.
id directory
Here is a list of all registered IDs and their applications:

ID | Application
`41544348 - "ATCH"` | FlacFile
`42534F4C - "BSOL"` | beSolo
`42554753 - "BUGS"` | Bugs Player
`43756573 - "Cues"` | GoldWave cue points (specification)
`46696361 - "Fica"` | CUE Splitter
`46746F6C - "Ftol"` | flac-tools
`4D4F5442 - "MOTB"` | MOTB MetaCzar
`4D505345 - "MPSE"` | MP3 Stream Editor
`4D754D4C - "MuML"` | MusicML: Music Metadata Language
`52494646 - "RIFF"` | Sound Devices RIFF chunk storage
`5346464C - "SFFL"` | Sound Font FLAC
`534F4E59 - "SONY"` | Sony Creative Software
`5351455A - "SQEZ"` | flacsqueeze
`54745776 - "TtWv"` | TwistedWave
`55495453 - "UITS"` | UITS Embedding tools
`61696666 - "aiff"` | FLAC AIFF chunk storage
`696D6167 - "imag"` | flac-image application for storing arbitrary files in APPLICATION metadata blocks
`7065656D - "peem"` | Parseable Embedded Extensible Metadata (specification)
`71667374 - "qfst"` | QFLAC Studio
`72696666 - "riff"` | FLAC RIFF chunk storage
`74756E65 - "tune"` | TagTuner
`78626174 - "xbat"` | XBAT
`786D6364 - "xmcd"` | xmcd

Copyright (c) 2000-2009 Josh Coalson Copyright (c) 2011-2016 Xiph.Org Foundation