There’s been a somewhat similar discussion before. Perhaps most of what could be achieved with reservable tags could be achieved with what’s suggested in this thread
I think what’s suggested there is basically taking XorName of a piece of MutableData and encrypting it with the private key of the issuer. Then the public key could be used to verify that the issuer was the one that created the MD. The name of a token would be something like mytokenprefix_token-number, so the names would go from mytokenprefix_0000 to mytokenprefix_10000 for example if there was to be 10 000 tokens, then these names would be encrypted with the issuers private key and added to the data and when the issuer goes public with the new token, all token MDs should already be created and they would just say that the valid tokens are tokens named mytokenprefix_0000 to mytokenprefix_10000.
Actually maybe encrypting it with the private key wouldn’t even be needed? If I understand correctly XorName is unique and is the hash of a name the user sets for a piece of MutableData. So if someone wants to issue a token then just creating MDs for all tokens mytokenprefix_0000 to mytokenprefix_10000 and saying that the only valid tokens are the ones with those names should be enough?