...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
static int const dim = /*user-defined*/;
This member of user-defined (partial) specializations of the vec_traits template must be a compile-time integer constant greater than zero that defines the size (number of elements, or dimension) of a user-defined vector type.