Hardware keyboard and the 'Sym' key
 

This does not seem to be documented anywhere, so...

What does that red Sym key (ie, reddot-Space) do?

Answer: It cycles the last character you typed through several variations

For A-Za-z it cycles the last character to various accented versions
For 0-9, it does nothing
For symbols, it gives you access to other similar symbols that are not on the keyboard

Examples:
( cycles [ { < <<, ) cycles opposite version of chars
/ cycles \ | (yay! backslash and pipe for linux!)
% becomes ^

Ah and red-dot red-dot is NUM LOCK

Anyone know how to generate a ctl key on the keyboard?