File Name
The texture's file name.
Color Space
The list of choices is populated with some OCIO spaces if configured and our builtin spaces if not. The default for out builtin system is "auto" which roughly means sRGB for all things 8-bit. The default when OCIO is configured it named "OCIO rules" and means using the OCIO config's file rules which are fancy pattern matching of the texture file names.
Default Color
These parameters define the input texture. The default colour is applied when no texture is found or when the texture lookup is outside the UV range.
...