My opinion is that DS wants to eventually get rid of SolidWorks all together, and they are working on a way to get to that end by slowly phasing out the "Legacy" SolidWorks products and getting (forcing) all the users to move to the Platform either xDesign or 3DX. Once they have a lot of t...

Not sure I understand your question, but here is an answer to what I think you are asking. The plane in your images would be perpendicular to the edge. There would be no x and y axis dimensions for it's definition since it would go infinitely in both directions. The blue box you see in the second im...