17.6.2.3 Supports
The Container invokes an enterprise Bean method whose transaction attribute is set to Supports as follows.
If the client calls with a transaction context, the Container performs the same steps as described in the Required case.
If the client calls without a transaction context, the Container performs the same steps as described in the NotSupported case.
The Supports transaction attribute must be used with caution. This is because of the different transactional semantics provided by the two possible modes of execution. Only the enterprise beans that will execute correctly in both modes should use the Supports transaction attribute.