Maintains assembly relationships when set. When this option is set, the relationships that you apply also control the behavior of the part when it is modified. For example:
If you apply an axial align relationship between two parts, they remain axially aligned when either part is modified.
When this option is cleared, you must still use assembly relationships to position the part in an assembly. However, instead of applying these relationships on the part, the software applies a ground relationship. Grounded parts do not update their positions in the assembly when other parts are modified.