This section contains tangency constraint descriptions of fixed, free, and floating alignment elements.
An alignment element's tangency constraint can be changed. For example, you can change a free curve to a floating curve. For more information, see To Work With Changing Alignment Constraints.
Note: If alignment elements are tangential, the overall alignment length does not change when a tangency constraint is changed. If alignment elements are not tangential, the overall alignment length may change when a tangency constraint is changed.
Fixed Element (Not Constrained)
A fixed element has the following characteristics:
- It is defined by specifying parameters, such as points or radius.
- Its parameters are fixed in their position. Only you can change the parameters that define this element.
- It is not dependent on any other element to define its geometry or to maintain tangency, but its length can be affected by another element that is attached to it.
- It can be initially created with a tangency association. Fixed elements that start from the beginning of another fixed element can be initially straight to the other element, but the tangency is not maintained when either element is edited.
Floating Element (Constrained by Preceding, or Constrained by Following)
A floating element has the following characteristics:
- It is defined by the parameters that you specify and is always straight to one element.
- It is always straight to the element it is attached to. A floating element cannot be attached to a free element, but a free element can be attached to a floating element.
- It can be attached only to another floating element or a fixed element.
- It is dependent on being straight to one other element to define its geometry.
Free Element (Constrained on Both Sides)
A free element has the following characteristics:
- It is defined by the parameters that you specify and is always straight to an element before and an element after.
- It must have at least two other elements to add to.
- It is dependent on two other elements to define its geometry.
- It can only be attached between either two fixed elements, two floating elements, or one fixed and one floating element, but in any order.