COMSOL Multiphysics version 4.2a contains many new functions and additions to the COMSOL product suite. These Release Notes provide information regarding new functionality in existing products. It also outlines some additions that we intend to make in COMSOL Multiphysics version 4.3.
We have strived to achieve backward compatibility with the previous version and to include all functionality that is available there. COMSOL 4.2a is compatible with COMSOL 3.5a, COMSOL 4.0, COMSOL 4.0a, COMSOL 4.1, and COMSOL 4.2 with a few exceptions. Those exceptions are listed in this document.
In the menu to the right you will find release notes for each product.