Oracle:

CREATE INDEXTYPE

CREATE [ OR REPLACE ] INDEXTYPE [ schema. ] indextype
FOR [ schema. ] operator (paramater_type [, paramater_type ]...)
[, [ schema. ] operator (paramater_type [, paramater_type ]...)
]...
using_type_clause
[WITH LOCAL [RANGE] PARTITION ]
[ storage_table_clause ]
;

using_type_clause::=
USING [ schema. ] implementation_type [ array_DML_clause ]
array_DML_clause ::=
[ WITH | WITHOUT ]
ARRAY DML
[ ([ schema. ]type
[, [ schema. ]varray_type ])
[, ([ schema. ]type
[, [ schema. ]varray_type ])...
]
storage_table_clause::=
WITH {SYSTEM | USER} MANAGED STORAGE TABLES

Example

CREATE INDEXTYPE position_indextype
FOR position_between(NUMBER, NUMBER, NUMBER)
USING position_im;