Specifying a Text Anchor

I want to add some additional descriptive text within a question to link to from a question statement. I found the following in the user documentation:

"Text anchors allow you to link to content in the same question. For example, if you have a long disclaimer with various sections in your survey, you can use a text anchor to link to the top of each section—ultimately making it easier for your participants to navigate. Text anchors must be specified in the question in order to use this option."

However, It does not explain how to specify a text anchor.