For RSD, a yellow spool icon indicates that this thread is captive, that is, it has hit a breakpoint or has been stopped. You can view the registers and variables for this thread, if it is the current thread, or it is attached to a Code window. The asterisk indicates that this is the current thread.

If you start the thread running again, it is no longer captive.

For HSD, a yellow spool indicates the thread that was current when the processor stopped.