UNDER Privilege

You own any named ROW type that you create. If you want other users to be able to create subtypes under this named ROW type, you must grant to these users the Under privilege on your named ROW type.

For example, suppose that you create a ROW type named rtype1:
CREATE ROW TYPE rtype1 (cola INT, colb INT);
If you want another user named kathy to be able to create a subtype under this named ROW type, you must grant the Under privilege on this named ROW type to user kathy:
GRANT UNDER ON ROW TYPE rtype1 TO kathy;
Now user kathy can create another ROW type under the rtype1 ROW type, even though kathy is not the owner of the rtype1 ROW type:
CREATE ROW TYPE rtype2 (colc INT, cold INT) UNDER rtype1;

For more about named ROW types, see CREATE ROW TYPE statement, and the discussion of data types in the Informix® Guide to SQL: Reference and the Informix® Database Design and Implementation Guide.