[cm/signed/] with Ed25519-BLAKE2b with Merkle-tree hashing.
[cm/pub/ed25519-blake2b] public keys are used.

It is similar to [cm/signed/ed25519-blake2b], but
HashEdDSA mode is used with [cm/hashed/blake2b-merkle] hashing.

"ed25519ph-blake2b-merkle" algorithm identifier is used in signature.

Its /sigs/*/sign contents:
    sign-ed25519-blake2b {
        {field . {map}}
        {field a {str} =ed25519-blake2b}
        {field v {bin} len=64}
    }
    
    sign-ed25519ph-blake2b {
        {field . {map}}
        {field a {str} =ed25519ph-blake2b}
        {field v {bin} len=64}
    }
    
    sign-ed25519ph-blake2b-merkle {
        {field . {map}}
        {field a {str} =ed25519ph-blake2b-merkle}
        {field v {bin} len=64}
    }