When history is on and a command supports history, there is a relationship created between the “inputs” and the “output” or the result. It is a what I symbolically refer to as “one way” street.
You update the inputs, they drive the output or result.
The opposite is not true: changing the result will not change the inputs.
So knowing this, you can see why selecting both the curve and the dimension, caused the “History broken” message box to appear. You were trying to change the result of the ordinate dimension command. So the history was about to be lost.
Many commands support history. It can be quite helpful to revolve or loft curves with History on. Then you can change the input curves, by control point editing or by simple transformations. The changes will drive the resulting surface interactively. See more on History here.
I made a simple screen capture video to illustrate how Rhino history on linear and ordinate dimensions can work for you, Again avoid updating the result, and you should see the how history can help you. (History results can be nested too for some very interesting edits. For example, tween between two curves, loft between result of tween. Now when you edit the input curves, the tween and loft update. Many, many more cool examples of this.)
Hope this can make you a fan of history!
Mary Ann Fugier
McNeel Technical Support and Training