They may also be used for microtunneling. It can also be used for infrastructure. Phenytoin should generally not be used. Spiders can also be used as food. They have also been used in pedagogy. Sometimes they are even used interchangeably. Thus, 5A-3 could not be used for navigation. These are primarily being used for teleoperation. The technology has not been used commercially. However, diesel engines would not be used. Each lifeline may only be used once. Prefixes may not be used in combination. Intravenous immunoglobulin may also occasionally be used. Other prefixes, however, are also used. Vortioxetine is also used off label for anxiety.