This specifies the pseudowire's Layer 2 emulation type -- raw(1), where Ethernet frames are carried without their VLAN tag being preserved end-to-end, tagged(2), where VLAN tags are preserved across the pseudowire, or tdm(3), circuit emulation for legacy TDM/SONET-style traffic rather than Ethernet at all. This setting directly determines what a customer will see at the far end: a tagged PW preserves their VLAN structure across the provider network, while a raw PW strips it, and a mismatch between the configured type and what the customer's equipment expects will show up as either missing VLAN tags or unexpected double-tagging. A customer reporting their VLAN tags are disappearing across a supposedly Ethernet service is describing exactly the symptom of this being set to raw when tagged was expected.