17. nav
article
nav
nav article
aside
aside
header
article
18. nav
article
nav
nav article
aside
aside
header
article
19. nav
article
nav
nav article
aside
aside
header
article
20. Microdata
<div itemscope>
<p>My name is <span itemprop="name">Neil</span>.</p>
<p>My band is called <span itemprop="band">Four Parts Water</span>.</p>
<p>I am <span itemprop="nationality">British</span>.</p>
</div>
http://www.w3.org/TR/html5/microdata.html
21. custom data attribute
<div id='sunflower' data-leaves='47' data-plant-height='2.4m'></div>
<script>
var plant = document.getElementById('sunflower');
var leaves = plant.dataset.leaves; // leaves = 47;
var tallness = plant.dataset.plantHeight; // 'plant-height' -> 'plantHeight'
plant.dataset.plantHeight = '3.6m'; // Cracking fertiliser
</script>
http://www.w3.org/TR/html5/elements.html#custom-data-attribute