What are the details for a wrap around mortgage? How does this work?

I have been in the mortgage business for a long time and I don't know if I have ever heard the term "wrap around mortgage". Can you explain what you do know about it? Did Google return anything on a search? There a lot of different mortgages out there but that one doesn't sound good!
Here is a website I found with my own advice!
What Is a Wrap-Around Mortgage? (http://www.mtgprofessor.com/A%20-%20Wrap-Around%20Mortgages/what_is_a_wrap-around_mortgage.htm)

Maybe this will help.