.CONTINUE : Continues execution of a stopped program.
.SKIP: Skip over the next statement or statements.
.STEP: Executes one or more statements.
.STEPOVER: Executes one or more statements but do not step into routines.
.TRACE: Continue execution, display each line of code as it is executed.
BREAKPOINT: Set and clear breakpoints for debugging.
CODE_COVERAGE: Return line numbers of executed and un-executed code within a routine.
PROFILER: Analyze the performance of IDL code.
SHMDEBUG: Print debugging information for shared memory segments.
STOP: Halt the execution of a running program or batch file.