There are two main concepts of Language Environment condition handling: the stack frame-based model and the unique, 16-byte condition token that it provides to communicate information about conditions to Language Environment resources and services.

Language Environment uses stack frames to keep track of a routine's order of execution, and the exception handlers available for each routine. This ensures that conditions can be isolated and handled precisely where they occur in a routine.

One of the most useful features of the condition handling model is the condition token: a 16-byte data type that contains information about each condition. You can use the condition token as a feedback code or to communicate with Language Environment message services. Unlike a return code, which is specific to the caller and callee of a routine, a condition token communicates between all the routines involved in an application. A condition token contains more instance-specific information about a condition than a return code does.

HLL condition handling techniques are discussed in Language Environment and HLL condition handling interactions.