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

EdDSA with Edwards25519 is used similarly as in RFC 8032.
But BLAKE2b is used instead of SHA2-512 hash.
=> RFC 8032, EdDSA

Strict ZIP-0215 validation rules should be used while verifying the signature.
=> ZIP-0215

PureEdDSA *must* be used when no detached data exists and
"ed25519-blake2b" algorithm identifier is used in signature.

HashEdDSA *must* be used otherwise, using BLAKE2b-512 as a
hash, using "ed25519ph-blake2b" algorithm identifier for
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}
    }