This object represents port type whether it is carrying subrate circuits. structured : This is for SDT(Structured Data Transfer). This type of port supports following features: * intended to emulate point-to-point fractional DS1 or E1 circuit. * Synchronous timing * Fractional(Nx64 Kbps)DS1/E1 service (Contiguous timeslots only).You can map an Nx64 Kbps channel to any Virtual Channel(VC). unstructured : This is for unstructured data transfer(UDT) All the DS0 time slots are allocated. This type of port supports following features: * intended to emulate point-to-point DS1 or E1 circuit. * Synchronous and Asynchronous timing framingOnVcDisconnect : similar to unstructured during normal operation. In case of channel failure line data will be looped back towards line. strau : only one DS0 time slot is allocated. The value strau(4) value is not supported in CESM-8T1/E1 or CESM-T3E3. CESM-T3E3 card supports value unstructured(2) only.