When a loop is traced, the DO clause itself is traced on every iteration of the loop.

You can retrieve the trace actions currently in effect by using the TRACE built-in function.

The trace output of commands traced before execution always contains the final value of the command, that is, the string passed to the environment, and the clause generating it.

Trace actions are automatically saved across subroutine, function, and method calls. See Section 2.3, “CALL” for more details.

For debugging multithreaded programs using the TRACE keyword statement and the TraceObject class see Debugging Multithreaded Programs.