Now, 18 out of the 19 Chiral amino acids, they exist in their S absolute configuration form, and only 15 exists in the R absolute configuration form. Now, what do we mean by absolute configuration? Well, let's remember a little bit of organic chemistry. So in organic chemistry, in order to determine the absolute configuration, we have to prioritize the different types of atoms attached to this carbon. So we have the sensor Chiral carbon. And we basically give these four groups a value that ranges between one and four.