The Keep Existing Physical Constraints option in the Import Source Files dialog box enables you to merge or replace existing constraints when you import new or modified GCF or PDC files.
Select Keep existing physical constraints to preserve all existing physical constraints that you have entered either using one of the MVN tools (ChipPlanner, PinEditor, or the I/O Attribute Editor) or a previous GCF or PDC file. The software will resolve any conflicts between new and existing physical constraints and display the appropriate message.
The Keep Existing Constraints option is Off by default. When this option is Off, all the physical constraints in the newly imported GCF or PDC files are used. All pre-existing constraints are lost. When this option is On, the physical constraints from the newly imported GCF or PDC files are merged with the existing constraints.