Does anyone know the purpose of slot 4 in the 11503 module. I understand there are 3 physical slots, though what is slot 4?
IE.
YD07LB09# show chassis
Configuration for CSS11503-AC E0:
Product Name: CSS11503-AC E0 SW Version: 07.30.1.06
Serial Number: JAB0817L040 Base Mac Address: 00-0f-f7-1c-30-62
Slot Number Module Name Status
1 CSS5-SCM-2GE primary
2 CSS5-IOM-8FE primary
3 empty slot
4 CSS503-SM-INT powered-on
