default-clause:

1! WITH
2 DEFAULT
3? 
3 constant
3 USER
3 NULL
3 CURRENT_DATE
3 CURRENT_TIME
3 CURRENT_TIMESTAMP
3 cast-function-name (
3.1 constant
3.1 USER
3.1 CURRENT_DATE
3.1 CURRENT_TIME
3.1 CURRENT_TIMESTAMP
3.2 )

identity-options:

1 AS IDENTITY
2? (
2.1+ ,
2.1.0 START WITH
2.1.0.1! 1
2.1.0.1 numeric-constant
2.1.0 INCREMENT BY
2.1.0.1! 1
2.1.0.1 numeric-constant
2.1.0! NO MINVALUE
2.1.0 MINVALUE numeric-constant
2.1.0! NO MAXVALUE
2.1.0 MAXVALUE numeric-constant
2.1.0! NO CYCLE
2.1.0 CYCLE
2.1.0! CACHE 20
2.1.0 NO CACHE
2.1.0 CACHE integer
2.1.0! NO ORDER
2.1.0 ORDER
2.2 (1) 

2.3 )