Family Label Dimension Direction: Does it Matter?

[paul.ashley]

I am trying to control the distance of one element to another in a family by labeling the distance between the two.  I want one object to stay stationary and one to move in relation to it.  I'm having trouble with a particular family and to rule something out I'm wondering whether it matters which reference is selected first when creating the dimension to turn into a label.

[Alfredo_Medina]

Assume that you have two reference planes that are not pinned, and  you place a length parameter between them. You can create the dimension for the length parameter in any direction; it does not matter. When you change the value of the parameter, Revit will move the newer of the two planes. If you want to override that behaviour, you need to pin the newer reference plane, and only then the older one will move.