Chad Robertson flatbread?

In his most recent book, Bread Book, Chad Robertson describes his slab breads as "based on our classic baguette dough: it's leavened and flavored with poolish and leaven along with a little commercial yeast. But for slab bread, we add a portion of scalded flour." He goes on to say that they use lots of different flours for the scald, but most commonly durum flour. In the next paragraph he talks about using an overnight autolyze of just the flour and water, then mixing the scald, poolish, and leaven in the next morning.