Simulate change sets and drift

At NovaTech, your team manages stacks that drift over time. Use the change set and drift simulator to see how CloudFormation previews updates before applying them and detects when resources have drifted from the template.

The simulator shows a stack with four resources. Make changes to the template and see the change set preview (Add, Modify, Remove) with the Replacement indicator. Then switch to drift view to see resource statuses (IN_SYNC, MODIFIED, DELETED) with side-by-side expected vs actual values.

Question: A change set shows a Modify action on an RDS instance with Replacement: True. What does this mean?