Throughout SIMtrace-ice documentation we shall use the term DUS to mean Device
Under Study.  The purpose of SIMtrace is to study (or test) the behavior of GSM
phone handsets, modems and other phone-type devices (GSM ME) from the viewpoint
angle of their SIM interface, hence the GSM ME or other SIM-interfacing device
used in a SIMtrace setup is best thought of as the device under study.  Using
our acronym DUS throughout this body of documentation gives us the precision
needed in this project.