What happens when max-register-forward is exceeded?

Hi,

 

I'm trying to understand how max-register-forward and max-register-refresh work and would like to know what happens with REGISTERs when the max-register-forward is exceeded?

 

My current understanding is that the SBC will forward all REGISTERs to the REGISTRAR and as well update the expire time in the local cache as long as the max-register-forward is not exceeded. When the max-register-forward has been exceeded  the SBC will only forward the REGISTER where the expire time is less then half of the expire-interval and for all other it will only refresh the expire time in the cache but will not forward it to the REGISTRAR.