* HSQLDB 2.x is a newer version of HSQLDB that came after versions 1.7.2, 1.7.3, 1.8.0, and 2.0.
* HSQLDB 2.x has been developed based on the experience gained from extensive SQL compatibility tests and stress tests conducted by application vendors that use HSQLDB in their products.
* The persistence engine in HSQLDB 2.x is an improved and more robust version of the persistence engine used in version 1.8, which was in use for over 5 years.
