With Families that have multiple sides, it can be ambiguous as to which parameters relate to which sides.
Take the counter top example in the image above. It has both Width and Depth parameters for sides 1 and 2.
But with the use of an Annotation Family, which contains Symbolic Lines set to <Invisible lines>, the correct sides can be graphically identified easily and quickly.
See an example Family File at http://a360.co/1PzM5wZ
Consulting Technical Lead, A2K Technologies