How to interpret `!` in show route when a route was successfully inserted into the kernel table?

[Ivan Kurnosov via Bird-users]

Hi team,

can somebody please help interpret the following output:

```
10.50.0.1/32         unicast [static1 02:16:07.523] * (200)
        dev xfrm-40
10.240.224.2/32      unicast [hq 02:27:17.417] ! (100/?) [AS65020i]
        via 10.50.0.1 on xfrm-40
10.240.2.0/24        unicast [hq 02:27:17.417] ! (100/?) [AS65020i]
        via 10.50.0.1 on xfrm-40
```

The current (birdc) machine establishes an ipsec tunnel and 10.50.0.1 is a
firewall on the other side of the ipsec tunnel.

And kernel routes look like

```
10.50.0.1 dev xfrm-40 proto bird scope link src 10.80.1.76 metric 32
10.240.2.0/24 via 10.50.0.1 dev xfrm-40 proto bird metric 32
10.240.224.2 via 10.50.0.1 dev xfrm-40 proto bird metric 32
```

So, technically all works: packets flow as expected. It's only the `!`
exclamation mark and `(100/?)` question mark that I cannot interpret.

Is it something I should worry about?

-- 
With best regards, Ivan Kurnosov