10 Declarations [dcl.dcl]

10.1 Specifiers [dcl.spec]

10.1.2 Function specifiers [dcl.fct.spec]

A function-specifier can be used only in a function declaration.
function-specifier:
	virtual
	explicit
The virtual specifier shall be used only in the initial declaration of a non-static class member function; see [class.virtual].
The explicit specifier shall be used only in the declaration of a constructor or conversion function within its class definition; see [class.conv.ctor] and [class.conv.fct].