802.1Q tunnel customer VLAN mapping和的含义是什么802.1Q tunnel provider VLAN mapping？

Shows 802.1Q (QinQ) tunnel information.
802.1Q tunneling allows layer 2 VPN connectivity between sites by encapsulating 802.1Q trunk traffic inside another 802.1Q trunk.
Command Syntax
Command Modes Syntax Description
show dot1q-tunnel [interface {<interfaceName>| {port-channel <portChannel>}}]
show dot1q-tunnel {customer | provider} vlan mapping [interface {<interfaceName>| {port-channel <portChannel>}}]
show dot1q-tunnel encapsulation [interface {<interfaceName>| {port- channel <portChannel>}}]
Command Default Examples
#show dot1q-tunnel interface xe1
#show dot1q-tunnel interface port-channel 3800 #show dot1q-tunnel customer vlan mapping
118
Privileged Mode
interface
interfaceName
port-channel
portChannel
#
Show 802.1Q tunnel configuration on the specified interface.
Interface to show information for.
Show 802.1Q tunnel configuration on the specified port channel.
Port channel to show 802.1Q tunnel configuration information for.
encapsulation
vlan mapping
customer
provider
interfaceName
This command has no default settings.
ONP – Layer 2 Commands
Displays 802.1Q tunnel stacked VLAN configuration.
Displays 802.1Q tunnel VLAN mapping information.
Displays 802.1Q tunnel customer VLAN mapping information.
Displays 802.1Q tunnel provider VLAN mapping information.
Name of an interface port. For example, xe1.

我不明白这四行：

Displays 802.1Q tunnel stacked VLAN configuration.
Displays 802.1Q tunnel VLAN mapping information.
Displays 802.1Q tunnel customer VLAN mapping information.
Displays 802.1Q tunnel provider VLAN mapping information.