WW2 Italian military abbreviation for your interpretation please

[dtrapnell]

As the attached image shows,  an Italian POW in India wrote home and gave his rank as "C.N.S."
Please will someone tell me what this means?
I cannot find it in my list of Italian military ranks.
An Italian postal historian does not know. He wonders if it might be Chaplain service ???

[usjoeden]

Hi David,
Here's an idea from my brother-in-law, a "maffioso de Palermo", he guess that it could be
Campania Navale Sergente
The last word means Underofficer
Regards

Ulf

[dtrapnell]

BRILLIANTISSIMO!
Many thanks.
Cordialmente
David