operator class

Hello

I have just started with postgreSQL.

I have a file with the following commands :

CREATE TYPE t_cod_t_activ AS (

cod_t_activ CHAR(10)

);

CREATE TABLE tip_activ (

id_tip_activ t_cod_t_activ,

des_t_activ t_des_t_activ

);

CREATE INDEX i_tip_activ ON tip_activ (id_tip_activ bpchar_pattern_ops);

When the CREATE INDEX is executed, this error shows:

ERROR: operator class "bpchar_pattern_ops" does not accept data type
t_cod_t_activ

Does it mean that I cannot create an index on a field wich is of a type
defined by the user?

I need that id_tip_activ be PRIMARY KEY.

Thanks and best regards

Miguel Ibáñez