// A child Inline element for the new Underline element.
Run runx = new Run("Text to make underlined.");

// After this line executes, the new element "underx"
// contains the specified Inline element, "runx".
Underline underx = new Underline(runx);

// A child Inline element for the new Underline element.
Run runx = new Run("Text to make underlined.");

// An empty paragraph will serve as the container for the new Underline element.
Paragraph parx = new Paragraph();

// After this line executes, the new element "underx"
// contains the specified Inline element, "runx".  Also, "underx" is
// inserted at the point indicated by the insertionPosition parameter, 
// which in this case indicates the content start position in the Paragraph 
// element "parx".
Underline underx = new Underline(runx, parx.ContentStart);

// Create a paragraph and three text runs to serve as example content.  
Paragraph parx = new Paragraph();
Run run1 = new Run("Text run 1.");
Run run2 = new Run("Text run 2, make underlined.");
Run run3 = new Run("Text run 3.");

// Add the three text runs to the paragraph, separated by linebreaks.
parx.Inlines.Add(run1);
parx.Inlines.Add(new LineBreak());
parx.Inlines.Add(run2);
parx.Inlines.Add(new LineBreak());
parx.Inlines.Add(run3);

// After this line executes, the selection of content
// indicated by the "start" and "end" parameters will be
// enclosed by the new Underline.  In this case, the new Underline
// will enclose the second text run, "run2".
Underline underx = new Underline(run2.ContentStart, run2.ContentEnd);