Détrempe
The détrempe is the base dough for lamination, into which the butter block is later enclosed. It is typically flour, water or milk, salt and a little sugar — plus yeast and a small amount of butter for croissant dough.
It is mixed to moderate gluten development: the dough should be homogeneous but not too elastic. Over-developed gluten resists rolling, so the dough contracts and tears the butter layer. Under-developed gluten will not hold the layers at all.
After mixing, the détrempe always rests in the fridge: the gluten relaxes, the dough cools to the temperature of the butter, and both take on comparable plasticity. It is often rolled into a rectangle before chilling, which makes enclosing the butter easier.