BGP - Confusion

Hello all,

A little confused here about one topic regarding BGP (redistribute)

When we use “redistribute osfp/eigrp/is-is” it will show you in the BGP summary a “?”
If i use “redistribute osfp/eigrp/is-is/ route-map XXX” it will show you as an “i”

So my question is, what field of the packet does it change to make it at the eyes of the router an “i” instead of an “?” (just by using the route map command) What is happening behind the scenes here, anyone?