able is left undefined.
If the variable already exists,
it is set to <I>value</I> if <I>value</I> is specified
or left unchanged if no <I>value</I> is given.
Normally, <I>name</I> is unqualified
(does not include the names of any containing namespaces),
and the variable is created in the current namespace.
If <I>name</I> includes any namespace qualifiers,
the variable is created in the specified namespace.  If the variable
is not defined, it will be visible to the <B><A HREF="namespace.html">namespace which