Sharepoint Hacks - field visibility

I've had a few people trying to use the replacement New/Edit list form hack I posted a  week or  two ago, and struggling to get the correct set of fields to display so I've written a couple of followup wiki entries:

Hopefully these will prove useful for anyone trying to make use of these hacks, and provide enough hints to implement something functional with the code snippets.
Written on November 19, 2007