 So by now, you should have started to get a feel for the alpha-slash-beta alternating alpha-beta-alpha-beta structures versus alpha-plus-beta, segregated regions of alpha helices and beta sheets. I'll show you two more of the latter. This is a small protein called ribosomal protein S6 and here you can start to, the reason, even if I did not show you the loops, you should be able to say that that's alpha plus beta because just look at the directions of the beta strands. When the beta strands are anti-parallel, it has to be a separate region, while if the beta strands are parallel, they have to mix up with the alpha helices. This is another protein called lysosine and hydrolysis peptide glycans in bacterial cell walls. Exactly what it does, not super important here, too. You see the pattern of the beta strands. It's an anti-parallel beta sheet and that's where you should be able to say instantly that that is an alpha plus beta fold. So with that type of rules, it actually gets easier to classify them, although when you see these as first sight, you might argue that, but it's super difficult to say is this a separate region or not. Again, the topology of the secondary structure elements will surprisingly make this a very clear distinction and that's why we only have two of them. Either it's alpha-plus-beta or alpha-plus-beta. But as I showed you in ATH, the complication is that you can have one part of a large protein that's alpha-slash-beta while another part that's alpha-plus-beta. The definition doesn't save me from that.