While researching a corrupt block on 11g SE, we came across a number of objects that were compressed according to the data dictionary.
How could that be? Compression is not a feature of SE, or so we thought.
The objects in question were all indexes. In fact, Oracle creates compressed indexes in ?/apex/core/tab.sql even though we are on SE.
Further investigation lead me to Doc 1084132.1 which calls the feature "Basic table compression".
Just something to be aware of.