Refined VLAN tag — payload narrows by shape (IPv4 / IPv6 / ARP / PPPoE
Discovery / PPPoE Session / one further nested VLAN tag / raw bytes),
dispatched by the tag's own encapsulated EtherType. This is what
vlanFrame``(1) produces, the depth used at every true root
(inetFrame, sllInetFrame).
Usage
import { type VlanRefined } from ".";