IINM, CPU and GPU are the only one that utilize +12V rail whereas +5v are for optical drives and HDD. Not quite sure about +3.3V rail though.
As for (-) rails, nowadays, there aren't much hardware that utilize it.
Anyhow, I am not quite sure regarding these. Sorry if any info is wrong.
Maybe you could use some spoiler to make it more neat and organize. Just a suggestion though.
The newbie guide to power supply units, Questions and comments are welcomed