david 42 hit the nail on the head. Only specialty grains that have undergone a special heat stewing process, and malts that have been roasted, and have had their starches converted to sugar inside the kernels, can be steeped IE..caramel a.k.a. crystal malts, roasted barley, chocolate malt, black patent malt etc. All that is occurring during the steep is to extract the already converted sugars, flavors and the colors from the grains.
All other malts of the two row, and six row variety, classified as base malts and kilned malts must be mashed at strict temperatures and times in order to activate enzymes that were created during the malting process. These enzymes, in turn, convert the starches in the kernels into fermentable sugars.
John