Substrings Name S’abonner

Hi, we have a lot of label [b]without a data source name[/b]. if i want to work automatically with (or other)
// Open a format document.
LabelFormatDocument btFormat = btEngine.Documents.Open(@"C:\label1.btw");
Console.WriteLine("SubString Name: " + substring.Name
+ ", SubString Type: " + substring.Type
+ ", SubString Value: " + substring.Value);

how i can catch the objects in label?
Thanks