Flow Designer is a graphical tool that allows users to automate processes in ServiceNow without coding. The following are supported by Flow Designer:

Call a subflow from a flow. This is a feature that allows users to invoke a subflow, which is a reusable unit of logic, from a flow. This can help simplify complex flows and avoid duplication of logic.

Use Delegated Developer. This is a feature that allows administrators to delegate the development and maintenance of flows and actions to users who are not administrators. This can help distribute the workload and empower non-admin users to create automations.

Run a flow from a MetricBase Trigger. This is a feature that allows users to trigger a flow based on a MetricBase query, which is a way of analyzing time-series data in ServiceNow. This can help automate actions based on data trends and patterns.

The following is not supported by Flow Designer:

Test a flow with rollback. This is not a feature of Flow Designer, but of Automated Test Framework (ATF), which is a tool that allows users to create and run automated tests on ServiceNow applications and features. ATF supports testing flows with rollback, which means reverting any changes made by the flow during the test execution. References: Flow Designer, Automated Test Framework