What kind of "Traits" are used/defined in the C++0x Standard

A trait in C++ encapsulates a family of operations that allow an Algorithm or Data Structure to operator with that type with which it is instantiated. char_traits are an example for grouping string- and file-required functions.

But not all traits have "trait" in their name, right? numeric_limits comes to mind. Is this a "Trait", too? Even without the name "trait" in it?

So, are there other Templates that could/should be considered a "Trait"? Besides the examples I found:

• allocator_traits how to get memory
• pointer_traits how to access an object indirectly
• type_traits meta programming
• char_taits for sequence of symbols
• iterator_traits how to get forward, backward and to the element
• regex_traits for... regexes.

I guess, what I am asking, too, is there a pure definition for traits?

Some things I am especially unsure about are:

• numeric_limits mentioned above
• <chrono>s customization "traits", [20.11.4], i.e. duration_values
• what about Hashing? Can the functor hash<> be considered to be a trait?
• If thats the case, are not all requirements "traits", like "CopyAssignable", etc?
• And then, are the abandoned "Concepts" the ultimate "trait"-Definition?

Update: The question what exactly makes a trait a trait seems a bit controversy in the details. Maybe a another question could be answered: Is there a comprehensive list which of the trait-like classes are new to C++0x, and which ones have already been in C++03? Maybe someone knows of a link to somewhere?