how does the stl's multimap insert respect orderings?

Question

I have some data which come with a integer index. I am continuous generating new data which needs to added to the collection of data I have, sorted by that index, at the sa

Answer 1

It seems the new standard (C++11) changed this:

The order of the key-value pairs whose keys compare equivalent is the order of insertion and does not change.^{[cppreference]}

I'm hesitating to use it though, as this seems like a detail easily overlooked when modifying the standard library to be C++11 compliant and it's the sort of detail that will silently cause errors if your compiler's library failed to implement properly.