The crafting system, basically, takes a textual representation of your recipe (for instance, a 3x2 recipe could be 'aab', 'cdd') and an explanation of what each character in the recipe is (for instance {'a', Item.apple, 'b', Item.redstoneTorch, etc}). This is what Greg was trying to explain earlier with the examples, and you'll note his examples follow the rule.
The boolean that shows up in the middle (in our examples, it's always false) allows you to specify a shapeless recipe.