False. The C standard had no consideration for thread semantics prior to C11, and C11's memory model is literally and explicitly derived from C++11's memory model (which itself is adapted from Java 5's memory model). All of the discussions about how the memory model semantics for C11 and C++11 actually work take place entirely within the C++ standards committee, as is true for most new C language features these days (with the C committee largely designing merely the spellings of the new features).