And the L simply means it's the other type of anantomer. And we'll see exactly what the DNL represent in just a moment. So, once again, the simplest sugars are a monosaccharides and we call them carbohydrates because the empirical formula tells us they consist of carbon as well as water molecules. So monosaccharides can either be aldehydes or they can be ketones. Aldehyde containing monosaccharides are known as aldosis, and ketone containing monosaccharides are known as ketosis. So the smallest functional monosaccharide, as we said, in just a moment, contains an N value of three.