What is a Survival Knife?

What is a survival knife? I've done some thinking about that and how to better organize this blog. What I've come up with is six types of survival knives:

1. Bushcraft - This knife is used for wilderness survival tasks like skinning game and light woodcraft. Examples include mora, Bark River, and even class Buck knives.
   
2. Chopper - This knife is used for heavy wood work, essentially replacing an axe or machete.
3. Rescue - This knife is used for very hard use urban rescue tasks. Examples include the Cold Steel SRK and the Gerber LMF II ASEK.
   
4. Pocket - This knife is used for every day carry or in small kits but can perform some of the above tasks.
5. Hollow - This knife has a hollow handle of some sort to carry a survival kit.
6. Multitool - More than just a knife.