bunker codes

Hello

A1) xxx ready xxx under construction
A2) xxx ready xxx under construction
A3) xxx ready xxx under construction
B1) xxx ready xxx under construction
B2) xxx ready xxx under construction
B3) xxx ready xxx under construction
III B) xxx meters ready xxx meters under construction

I'll find in a german radio message about italian coastal situation intercept from British forces
Which A1 A2 etc... stand for? I suppose it's the the kind of construction. IIIB could be the wired fence meters?

Thanks
Abaco