LOCAL_TRANSACTION with out start and commitTransactions...not an issue?

Hi All,
What is the exact difference(and functionality)between NO_TRANSACTION and LOCAL_TRANSACTION that will be specified while creating JDBC Connections?
If we omit startTransaction and commitTransaction for LOCAL_TRANSACTION, it still woerks fine, but why webMethods provided these two types.
I did not find this behaviour in the JDBC Adapters user’s guide PDF
Referred this Link, but it still requires more clarafication http://wmusers.com/forum/showthread.php?t=13821&highlight=LOCAL_TRANSACTION

With NO_TRANSACTION, you cannot perform a rollback/commit as the adapter does it automatically after every jdbc call.

With LOCAL_TRANSACTION, you don’t have to use start/commit/rollback. The ART performs that for you implictly. Or you can explicitly control the start/commit/rollback by putting them into your flow services.

if you are not using explicit start and commit transaction statements, then you can only have one adapter connection that has a local transaction in a single wm flow i.e if you are not using start,commit and roll back u can have use only one connection in that flow service. If you want to use more then one adapter service with different connection then you will have to use start,commit, and roll back !!