Question on DR$ tables/indexes

Hi All,

I am experiencing an issue where there are a lot of updates being recorded in the DR$ and DR$A indexes.  I would like to know what these indexes are and how they are being used?

Here is the query I ran to see the activity in the DB:

select table_name, inserts, updates, deletes, truncated, timestamp

from dba_tab_modifications order by   2 desc

Results:

TABLE_NAME                              INSERTS  UPDATES  DELETES  TRUNCATED  TIMESTAMP

DR$MULTIASSETLOC_T2DX$K 785557 0 0 NO 03-SEP-15

DR$WORKORDER_NDX39$K 767050 0 3 NO 10-SEP-15

DR$WORKORDER_NDX16$K 767047 0 0 NO 10-SEP-15

DR$WORKORDER_NDX14$K 767047 0 0 NO 10-SEP-15

DR$WORKORDER_NDX12$K 767047 0 0 NO 10-SEP-15