Documentation for implementation-defined behaviors

Documentataion for implementation-defined beahviors are part of conformance to ISO C++. The standard requires them to be defined in the documentation of the implementation. Where are they maintained?

Currently, nothing about them are in docs, which can be a surprise, e.g. compared to libc++.

I find no entry about them on learn.microsoft.com. There was a bug but closed as "not a bug" in favor of the language reference.

Despite the status of the core language documentation (irrelavant here) and the fact of lacking a list of implementation-defined behavior as the index of the standard, I find some are too insufficient to be usable at all. For example, list::iterator is an alias of some implementation-defined type, and the document just renders it "implementation-defined", but where is the definition? Although libstdc++ effectively undermines this as unspecified and libc++ is simply missing such entries (hence buggy), copying the text of "implementation-defined" as-is from the standard should not be complete.

For the sake of maintability, the documentation of the library can be better maintained in this repository. If this is out of the scope, clarification and pointing to the right place in README.md should improve the status a bit.

Start by reviewing the repository's docs directory and README.md, then compare their coverage with the ISO C++ implementation-defined behavior index and the linked libc++ documentation. Determine whether the STL library's implementation-defined behaviors belong in this repository or should be documented elsewhere; done means either adding an agreed documentation location or clarifying the correct scope and pointer.