undocumented

This is not really anything new - in fact Tanel Poder has already blogged about it a while ago. Tanel has specifically covered the handling of "urgent" TCP packets and how this could be used to signal a "cancel" to another process, however this only works on Unix environments and not with Windows SQL*Plus clients. In Tanel's article it is also mentioned that there is an officially documented way of doing this via the Resource Manager if you happen to have an Enterprise Edition license.

In my quick tests however the call to DBMS_RESOURCE_MANAGER.SWITCH_CONSUMER_GROUP_FOR_SESS using "CANCEL_SQL" as consumer group only errors out with ORA-29366 saying that the specified consumer group is invalid.