We see lots of code posted here with #include <conio.h> .
That stuff based on Borland C++ which predates standardization, includes templates, exceptions, RTTI. In the PC World, it was the only decent popular C++ compiler. It's probably just referred to as Borland C++.
how well do you want to describe it?
there is c with classes, the original c++.
this had a variety of relatively small changes over the years until the STL came along. The stl was poorish at first, with the libraries slow, best practices yet to be established, and many features we love today not quite in place, but even so it quickly came into its own and became a game changer once the implementations were beefed up and best practices were published (eg effective stl original series).
so basically you have pre stl, post stl, 98, 11 / 17 versions, and if you need finer grained than that, you need to probably specify a compiler generation (eg turbo 3.0 or Borland builder or MSVC 2008 etc) to clarify what was available. For example if asked I have to say my .mat to c++ matrix library was written in pre-stl style.
The previous model of C++ updates was effectively "when it's ready". This gave us a thirteen year wait (excluding the minor bugfix of C++03), and a very clear difference between C++11 and C++98; a very clear modern and legacy C++.
Now that the committee has moved to a model of an update every three years, we won't see a difference of that magnitude again and a simple "legacy" and "modern" label becomes unhelpful.
I think we're already finding the term "modern" to be unhelpful, as for the older programmers it still means "C++11 and up", but there are now C++ programmers who were ten years old in 2011 and for whom anything before C++17 is old-school.