+/**
+ * DOC: VLAN tag manipulation.
+ *
+ * &struct sk_buff handling of VLAN tags has evolved over time:
+ *
+ * In 2.6.26 and earlier, VLAN tags did not have any generic representation in
+ * an skb, other than as a raw 802.1Q header inside the packet data.
+ *
+ * In 2.6.27 &struct sk_buff added a @vlan_tci member. Between 2.6.27 and
+ * 2.6.32, its value was the raw contents of the 802.1Q TCI field, or zero if
+ * no 802.1Q header was present. This worked OK except for the corner case of
+ * an 802.1Q header with an all-0-bits TCI, which could not be represented.
+ *
+ * In 2.6.33, @vlan_tci semantics changed. Now, if an 802.1Q header is
+ * present, then the VLAN_TAG_PRESENT bit is always set. This fixes the
+ * all-0-bits TCI corner case.
+ *
+ * For compatibility we emulate the 2.6.33+ behavior on earlier kernel
+ * versions. The client must not access @vlan_tci directly. Instead, use
+ * vlan_get_tci() to read it or vlan_set_tci() to write it, with semantics
+ * equivalent to those on 2.6.33+.
+ */
+