nwDecIVHostMapType is a read-write enumeration describing the nature of a host-map entry, where setting it to invalid(2) disassociates the circuit or interface from that mapping, and the MIB notes it is implementation-specific whether the agent then actually removes the entry from the table, so management stations should be prepared for the entry to simply be marked invalid rather than disappear. An admin sets this to dynamic(3), static(4), or inactive(5) to classify how a host mapping was learned or should be treated, and uses invalid(2) to retire an entry. For example, an admin who manually configures a fixed host-to-interface mapping would set nwDecIVHostMapType to static(4) rather than leaving it as a dynamically learned dynamic(3) entry.