I found out about some interesting stuff while reading the spec for list items. Check it out if you want to learn any more!
This is a standard ordered list, but with a twist: you don't actually need the closing list tag on each item for it to be valid:
You can reverse the order of a list using the reversed attribute
You can change the order on a list item by setting it's value attribute. The list will continue counting up or down from that point, depending on whether reversed is specified.
An interesting side effect of this is, if you set a value on a list in reverse order, it will start using negative numbers