The band track form can be a top-level form but is also found as the data part of a Track Form. It is organized as follows:
RIFF( 'DMBT'
    [<bdth-ck>]     // Band track header
    [<guid-ck>]     // GUID for band track
    [<vers-ck>]     // Optional version info
    [<UNFO-list>]   // Name, author, copyright info, comments
    <lbdl-list>     // List of band lists
    )
 The subchunks of the form are as follows:
<bnth-ck> -> bdth( <DMUS_IO_BAND_TRACK_HEADER> )
 This optional chunk contains header information for a band track. The only data in the structure is a flag for automatic downloading.
For the next three elements, which are optional, see Common Chunks.
The last chunk contains one or more bands:
<lbdl-list> -> LIST( 'lbdl'
    <lbnd-list>...
    )
 Each band is encapsulated in a list of the following type:
<lbnd-list> -> LIST( 'lbnd'
    <bdih-ck>
    <DMBD-form>
    )
 The band list begins with a header:
<bdih-ck> -> ( <DMUS_IO_BAND_ITEM_HEADER> )
 The header is followed by a Band Form containing information about the instruments in the band.