You're right, crazy question
An index, whatever its type, is designed to work on a relational or object instance column, not on a class definition.
I don't know what you had in mind, but to give some sense out of your question you could imagine doing something like this :
- create the type definition
- create a table to hold instance of this type
- create the index on the nested table column
CREATE TYPE mytype AS TABLE OF XMLTYPE; CREATE TABLE mytable (myobj mytype) NESTED TABLE myobj STORE AS mytable$nt ( XMLTYPE COLUMN column_value STORE AS SECUREFILE BINARY XML ) ; CREATE INDEX mytable_uxi ON mytable$nt(column_value) INDEXTYPE IS xdb.xmlindex ;