identifier = lNode.getIdentifier();
labelOrdinal = this.labels.get(identifier);
labelOrdinal = -1 * labelOrdinal; // Store NOT node as -ve ordinal.
}
if (labelOrdinal == 0) {
throw new InvalidLabelException("Invalid visibility label " + identifier);
}
labelOrdinals.add(labelOrdinal);
} else {
List<ExpressionNode> childExps = ((NonLeafExpressionNode) node).getChildExps();
for (ExpressionNode child : childExps) {