Set = (S,E,T), [SP], SetItem, { ',', SetItem } ;
SetItem = (PropertyExpression, [SP], '=', [SP], Expression)
| (Variable, [SP], '=', [SP], Expression)
| (Variable, [SP], '+=', [SP], Expression)
| (Variable, [SP], NodeLabels)
;
Variable = SymbolicName ;
NodeLabels = NodeLabel, { [SP], NodeLabel } ;
NodeLabel = ':', [SP], LabelName ;
LabelName = SchemaName ;