\begin{gomcode}[caption=Signature algébrique correspondant au métamodèle de la
  figure~\ref{fig:graphmm}.,label=code:signalgGraph]
Graph = opGraph(nodes:NodeList, arcs:ArcList)

Node  = opNode(name:String, graph:Graph, incomings:ArcList, outgoings:ArcList)

Arc   = opArc(weight:Int, graph:Graph, source:Node, target:Node)

NodeList = opNodeList(Node*)

ArcList   = opArcList(Arc*)
\end{gomcode}