AMOS Music Bank
AMOS Music Bank is a subtype of AMOS Memory Bank.
An "AMOS BASIC Konverter" format has been claimed to exist, with a .ambk extension, but there is little evidence of this, so it may be a garbled reference to the AMOS Music Bank format with its .abk extension (AmBk does appear as an ASCII identifier within AMOS Memory Bank files), and may just refer to such files as created by the Konverter software (References:   ) -- this seems to be different software from the "Konvertor" software referred to below, but is hard to find an actual runnable copy of.
Files begin with ASCII "
AmBk", and have "
Music " at offset 12.