How to Get the Chassis Serial Number in IOS-XR

This caught me out the other day and I had to find the answer deep within a Cisco document. To hopefully save someone else having to wade through all that, the commands to find out chassis serial numbers on the ASR9k are as follows:

RP/0/RSP0/CPU0:nodename#admin
Thu Sep 25 14:15:16.645 BST
RP/0/RSP0/CPU0:nodename(admin)#show dsc
Thu Sep 25 14:15:27.080 BST
---------------------------------------------------------
           Node  (     Seq)     Role       Serial State
---------------------------------------------------------
    0/RSP0/CPU0  (       0)   ACTIVE  ABC2345X678 PRIMARY-DSC
RP/0/RSP0/CPU0:nodename(admin)#

Err.... simple?