What do those signify? Also curious about the "automatic alias replacing hash with tilde" comments.

The two characters are synonymous. We started with hashes, but as it turns out passing hash in a URL was too hard, so we introduced tilde as a synonym. That means a load of signals got a second equivalent name - we stuffed those new names in automatically.
HTH!

Ah... so what does a hash/tilde signify?

Ah, sorry: it signifies negation, or that a signal is active-low.

Ok, thanks. Added a note on it in the tutorial too.