regions

The Amazon Web Services Regions in which to update associated stack instances. If you specify Regions, you must also specify accounts in which to update stack set instances.

To update all the stack instances associated with this stack set, do not specify the Accounts or Regions properties.

If the stack set update includes changes to the template (that is, if the TemplateBody or TemplateURL properties are specified), or the Parameters property, CloudFormation marks all stack instances with a status of OUTDATED prior to updating the stack instances in the specified accounts and Regions. If the stack set update does not include changes to the template or parameters, CloudFormation updates the stack instances in the specified accounts and Regions, while leaving all other stack instances with their existing stack instance status.