I understand how to use a normal map, and methods for making it from a texture map, but the render option for this is a bit of a mystery because I have a render  not really a texture so I am trying to figure the real practical use of this is. Like a preview?  What is the best way to get a useable normal map out of Carrara? Got all the inagoni plugins. I know agrooves can have some advantages here also.

uhh.....as in render the pic, and RGB channels used to tell the direction of the normal XYZ?
then just use a formula in the color channel

or making a UV map with the normal info, same way, but bake it, not render

as for a use, atleast for the first one, i use it a lot to create displacement maps
it's easier for me to model than paint, so i model say head/foot boards of a bed
with a lot of swirling wood designs on them, then render the normals in RGB
use a displacement map making program, and a very high res model can be
taken down to a small texture file, and easily disabled in test renders, for speed

best i can understand your post =P

You can use a Carrara scene rendered to a normal map to give you a result which would be difficult using another method. For example, I put the detail on the coins in this gallery image in that way. Any time that you want to detail a flat surface but not use actual modeling it would be a good method to consider.

Yeah, it's not the clearest post. This refers to the render option available in carrara to render a normal map.
I set it to use the gbuffers and render to tif.  Because it looks like a rendered picture I was unsure. I could see using it on something kinda flat, like a coin, but in other instances, I don't know. Creating a normal map via rgb channels for a texture map in a 2d program I have done.  This one  being what appears to be a 2d render, particularly on non-plane-like objects I was not sure about. I do understand normal maps, but this particular feature seems unclear. Say, I have a face. I render a normal render to tif w/ the buffers. I don't see how that is going to make a good normal texture map for the face.