VLAN Tagging (IEEE 802.1Q)
From Zenitel Wiki
VLAN Tagging is the practice of inserting a VLAN ID into a packet header in order to identify which VLAN (Virtual Local Area Network) the packet belongs to. More specifically, switches use the VLAN ID to determine which port(s), or interface(s), to send a broadcast packet to.
VLAN tagging is supported by stations in the INCA family, IP Desktop Master Station V2, IP Desktop Master Station with Handset V2, IP Flush Master Station V2 and IP CROR Master Station V2.