Describes a special member function (that must always be a constructor) with an explicit Function-specifier
This describes an explicit special member function (that must always be a constructor). This has two mandatory attributes; name and value (see example below).
See ISO/IEC 14882:2003(E) 7.1.2 Function specifiers [dcl.fct.spec]
The explicit specifier shall be used only in declarations of constructors within a class declaration; see ISO/IEC 14882:2003(E) 12.3.1.