It is populated whenever Component to be Linked, Component to be Replaced
or Reference Parent drop down combos, left and right hand side "Method"
or "View Options" are changed.
It is populated with parent parts from the Product Structure table for the
selected component to be replaced. If View Parts is set to Show Active,
only parts, where the engineering change date is less than the current date
and the Link Status Code is equal to "A", or
Where the engineering change date is greater than the current date and
the Link Status Code is equal to "I", are displayed.