KangarooIceberg	::= {TopLevelNode}.
TopLevelNode	::= NodeName NodeLit.
NodeLit		::= "{" {ArcDefn} ["/" RuleSets] "}".

ArcDefn		::= NodeRef ":" WeightDefn.
NodeRef		::= NodeLit | "^" NodeName | NodeName NodeLit.
WeightDefn	::= <<literal integer>>.

RuleSets	::= RuleSet {";" RuleSet}.
RuleSet		::= Rule {"," Rule}.
Rule		::= {ArcApp} "->" {ArcApp}.

ArcApp		::= NodeApp ":" WeightApp.
NodeApp		::= NodeRefn | Var<Node>.
WieghtApp	::= WeightDefn | Var<Weight>.

Var		::= "$" Name.