It should follow the pattern already established by alter index, so
after the index name:
CREATE [UNIQUE] [ASC[ENDING] | DESC[ENDING]]
INDEX indexname [{ACTIVE | INACTIVE}]
ON tablename {(col [, col ...]) | COMPUTED BY (<expression>)}
[WHERE <search_condition>]
I'm also including ACTIVE here, though that should be default when it is
not specified explicitly.
Mark
--
Mark Rotteveel