No OPUS identifier in audioType (MP4AddAudioTrack)

[ar-visions]

MP4V2_EXPORT
MP4TrackId MP4AddAudioTrack(
    MP4FileHandle hFile,
    uint32_t      timeScale,
    MP4Duration   sampleDuration,
    uint8_t       audioType DEFAULT(MP4_MPEG4_AUDIO_TYPE) );

there seems to be no audioType for OPUS which is understandable since its so new. My thought is this audioType should be the FourCC identifier and not the uint8_t. Would it be acceptable to allow for this reduction in audio identifiers? When I load a mp4 container the track does not contain this uint8_t so I assume its a binding id to the FourCC?

[ar-visions]

Just wondering if we can get away with setting MP4_MPEG4_AUDIO_TYPE and using further identification afterwards?