What's the difference between libm.lib, libmmt.lib, and libmmds.lib?

Question

Intel describes libm.lib as a static library, libmmt.lib as a multi-threaded static library (/MT) and libmmds.lib as a multi-threaded static library (/MD) all implementing the LibM Math Library.

But don't you always have to choose either /MT or /MD? Why are there 3 static versions of the library on Windows, rather than just two?

Answer 1

This is for old VC6 that has a a runtime for single threaded application!! but for now you are correct, we don't have it any more!