private void SaveTableOfContents(ArrayList topics)
{
Document tocDoc = new Document(mTocTemplate);
// We use a custom mail merge even handler defined below.
tocDoc.MailMerge.FieldMergingCallback = new HandleTocMergeField();
// We use a custom mail merge data source based on the collection of the topics we created.
tocDoc.MailMerge.ExecuteWithRegions(new TocMailMergeDataSource(topics));
tocDoc.Save(Path.Combine(mDstDir, "contents.html"));
}