Structured error handling is an expansion of the original ABL error handling features, which are now referred to as traditional error handling features. While the new language features do provide you with a more robust error handling model, they coexist and interoperate with the traditional error handling features. Existing code will continue to work as is, and code using the new model can work with this existing code.
While both the new and the old language elements are now part of your set of error handling tools, the structured methodology that goes with the new model provides benefits that you will want to exploit immediately in your new programming projects.