A marked node is simply a node that is marked with an encrypted token received from the account's private key; this token can be decoded to show the specific PZM account address and balance that are associated with the node. The label placement act on a node adds a layer of accountability and trust, so that marked nodes are more reliable than those that do not have markings on the network. The more the balance of account is linked to a marked node, the more confidence is given to this node. While an attacker might want to mark a node to gain trust on the network and then use that trust for malicious purposes, the barrier to entry (the cost of PZM needed to build adequate trust) prevents such abuse.