C++ and C Standards are usually named after the year they are published in. For example, in C++, the original Standard was published in 1998, so it is called C++98, and its first correction, published in 2003 is called C++03.
For the next revision, it was supposed that the next Standard after would be done by 2008, but since it was uncertain, it was named C++0x, where the x stood for either 8 or 9. Though planning shifted and it is now called C++11. So, C++0x was the name for the standard before it was published. Once it was finalized in 2011 it was named C++11.