From HEXONET Wiki
Transfer / Trade ACK by
In the case that a transfer or a trade needs a separate approval, this can be done by different parties.
REGISTRY: Means that the domain-registry is able to approve the transfer.
REGISTRAR: Means that the losing registrar is able to approve the transfer.
REGISTRANT / CUSTOMER: In some cases the customer is able to approve a transfer / trade. It depends on the registry if the registrant or administrative contact of the domainname will be contacted.
BOTH: Both parties are able to acknowledge the transfer.
NONE: Nobody has to approve the transfer.