[c-nsp] debug mpls packet

[Andy Saykao]

Hi All,
 
Does anyone know what the middle number represents in a "debug mpls
packet" ( eg: {7963 6 254} )? 
I can't find this information anywhere.
 
router#debug mpls packet gigabitEthernet 0/2
Packet debugging is on on idb GigabitEthernet0/2
router#
Nov 17 16:26:07.670 AEDT: MPLS turbo: Gi0/2: rx: Len 97 Stack {7963 6
254} - ipv4 data
Nov 17 16:26:08.442 AEDT: MPLS turbo: Gi0/2: rx: Len 78 Stack {7963 6
254} - ipv4 data
Nov 17 16:26:11.882 AEDT: MPLS turbo: Gi0/2: rx: Len 82 Stack {18 0 254}
{2750 0 255} - ipv4 data
Nov 17 16:26:11.882 AEDT: MPLS turbo: Gi0/1: tx: Len 82 Stack {8878 0
253} {2750 0 255} - ipv4 data

{7963 6 254}
 
7693 = Label
6 = ???
254 = I presume is the TTL
 
What does the 6 represent??
 
In the other label, it's a ZERO instead {18 0 254} .
 
Thanks.
 
Andy

This email and any files transmitted with it are confidential and intended
 solely for the use of the individual or entity to whom they are addressed. 
Please notify the sender immediately by email if you have received this 
email by mistake and delete this email from your system. Please note that
 any views or opinions presented in this email are solely those of the
 author and do not necessarily represent those of the organisation. 
Finally, the recipient should check this email and any attachments for 
the presence of viruses. The organisation accepts no liability for any 
damage caused by any virus transmitted by this email.