gradual steep? Not sure what this is or how to add in BTP

[kipgordon]

So, I'm not sure what to call this but, a lot of the kit recipes that I use will have you put the grains in a grain bag and add it to the cold water in your brew kettle. Then you heat the water and remove the grain when it reaches a certain temperature.

First, what is this process called and second, how do I add that as a step in BTP?