Each CAD company seemed to be taking their own path, with no commonality or consideration of industry as a whole they either reflected their primary clients' wishes or went however they wanted. and manufacturing, design and military industries saw that this was bad. IN THE BEGINNING, there were no standards governing the means of 3D drafting. Anyway, I do understand everyone's frustration, and here's what I've gleaned of the standard's history. I'm not sure what was decided after the last meeting. I participate on the 14.41 S/C now, either on the support team or maybe as a member now. RE: ANSI standard for leaders ctopher (Mechanical) 7 Jan 10 23:09 I've been doing 3D annotation for over 10 years and it just seems like the standard has choked some of the benefit with these details. I would love to get on the 14.41 committee. But to people putting the annotation on only to have to edit it or adjust a default etc etc to control dots over arrowheads, pointing to surfaces instead of edges (which I don't particularly like, but don't think it should be illegal), and the whole relative plane thing is going to slow 3D annotation down reducing it's major benefit, TIME.
The query requirements are another major issue, but that is another thread, I am sure.
Meanwhile, in 3D the queries clearly identify the features that belong to the annotation. When within a "model view" that represents a 2D view, it makes sense to use a leader to an edge like we have done in 2D forever so that when the "model view" is shown or even printed, it looks like what the world is used to. Why not surfaces? For example a profile of surface(s)? I know that the leader can also just point to the surface(s) with the DOT, but consider acceptance of 3D annotation. The standard has an exception for leaders to point to edges of "features of size" if it provides a clearer understanding. Why does a leader line have to end in a DOT when associated to a surface? In 2D it makes sense, but in 3D What is the value? These sort of details are only going to lead to a pile of human errors frustrating people who want to implement 3D annotation. Why is it that most if not all the annotation has to be in the same plane, a parallel plane, or perpendicular plane to the feature? Who cares? It is 3D. One, more of the GD&T can be more organized and displayed in a single view. For example, why is that we can not use an extension line for feature control frames or datum feature symbols? In 3D, using the common 2D extension line permits numerous advantages. However, must of the "requirements" simply are not value added. I can understand the attempt to address the 3D environment.