Bowl blending?

No pics handy, but it's basically smoothing out the rough edges below the valve seats and blending the bottom cut into the bowl wall. Sometimes there are edges or lips left after a valve job and/or casting imperfections from the factory. It's a fairly easy and safe way to help smooth out the air flow. With outright porting throughout the whole port, you need to know where you should and shouldn't remove metal from because you could hurt the air flow. Could consider it very mild porting in the "valve bowl" area which extends down to the valve guide.

But you have to be very careful not to nick/cut the actual valve seats while doing it.