+ (output-attributes ,list? "An alist of attributes for the grob, to
+be included in output files. When the SVG typesetting backend is used,
+the attributes are assigned to a group (<g>) containing all of the
+stencils that comprise a given grob. For example,
+@code{'((id . 123) (class . foo) (data-whatever . @qq{bar}))} will produce
+@code{<g id=@qq{123} class=@qq{foo} data-whatever=@qq{bar}> @dots{} </g>}.
+In the Postscript backend, where there is no way to group items, the
+setting of the output-attributes property will have no effect.")