In this SQL statement, what is the partitioning criteria?

CREATE TABLE books_part

PARTITION BY RANGE (cell_id) (

PARTITION p0l VALUES LESS THAN (2),

PARTITION p02 VALUES LESS THAN (3) ,

. . .

PARTITION pl4 VALUES LESS THAN (15),

PARTITION pl5 VALUES LESS THAN (16),

PARTITION pl6 VALUES LESS THAN (MAXVALUE)

)

AS SELECT * FROM books;