Link created by user using any SQL tool, is identified from Enlighten. If this link is not a default one then It will have the sign "X" as you can see in the following example.
If you want to find from which SQL tool the link is created then, point the mouse over the link, then press the key F12. The link in the following example is created via Reference Finder:
Default link will not have the sign "X". following example represents a belong link: