Zebra

On a 2006 Civic, there is a fuse legend diagram under the top plastic fuse box (in the engine compartment). Some of the fuses are marked only with a large capital 'I' designation. The owners manual doesn't explain this symbol, nor can I find an explanation on-line. Are these undedicated spare fuses? The air conditioning condenser quit working, and it was the condenser fuse relay that was the problem - this fuse was marked with symbols indicating air conditioning. I switched out a fuse with the capital 'I' marking. assuming it was a spare - but I am not sure. Anyone know what the capital I symbol means?