Before release 6.10, exceptions for exception situations of the runtime environment that could be successfully handled in the program were defined exclusively as catchable runtime errors.
All catchable runtime errors are predefined in the system and assigned to the ABAP statements during the execution of which they may occur. Several runtime errors can be grouped together in an exception group and can be handled together under the name of the group.
As of release 6.10, an exception class is assigned to each catchable runtime error. This can alternatively be handled as a catchable runtime error or as a class-based exception, whereby the latter is recommended. Conversely, however, not all predefined, class-based exceptions are assigned to a catchable runtime error. Since Release 6.10, no new catchable runtime errors are created, and existing runtime errors that should be made ready for handling are no longer converted to catchable runtime errors. Instead, exception classes are assigned to them.
In the ABAP keyword documentation, the possible class-based exceptions and the assigned catchable runtime errors are listed after each key word. The following two sections contain a compilation of all catchable runtime errors, their assignment to exception groups, and the exception classes assigned as of release 6.10.
Catchable runtime errors cannot be triggered explicitly, but are only triggered implicitly by the runtime environment.