// For complete examples and data files, please go to https://github.com/aspose-words/Aspose.Words-for-.NET
Document doc = new Document();
Shape shape = new Shape(doc, ShapeType.TextBox);
TextBox textBox = shape.TextBox;

if ((textBox.Next != null) && (textBox.Previous == null))
{
    Console.WriteLine("The head of the sequence");
}

if ((textBox.Next != null) && (textBox.Previous != null))
{
    Console.WriteLine("The Middle of the sequence.");
}

if ((textBox.Next == null) && (textBox.Previous != null))
{
    Console.WriteLine("The Tail of the sequence.");
}