NHEDB is an extensible DBMS based on the relational DBMS(NHDB).The data model of the system is an extended relational model which supports ADT and NF2.

• NHEDB是在关系DBMS（NHDB）基础上研制的可扩充DBMS，系统采用扩充关系数据模型（主要是支持ADT和NF2。