Defer Modification
DEFER specifies that geometry should not be modified until the user makes an explicit request. This method will improve performance, because the drawing will be updated only once — even if the values of several parametric dimensions have been modified.
DEFER is actually necessary when a set of parametric dimension modifications do not have valid intermediate geometry. For example, consider a triangle with sides of lengths 3, 4, and 5:
Triangle Requiring DEFER
It would not be possible to change the side lengths to 30, 40, and 50 using IMMEDIATE, because no valid triangle can be created with a combination of old and new lengths.
 | Often a combination of IMMEDIATE and DEFER is useful when several parametric dimensions need modification. |