More often than not, a disk is using the Master Boot Record (MBR) partition table format. However, due to the limitations imposed on the MBR partitioning scheme (eg. maximum 4 partition entries), GUID Partition Table (GPT) disks are becoming a popular alternative. You can determine which partitioning scheme a particular disk is using by using the 'Raw Disk Viewer' module.
Select the physical disk (without a partition) in the drop-down list. This is important as the MBR and partition table are outside of the partitioned space.
Ensure the cursor is within the first sector (Sector 0) of the disk. In the Data Interpreter window, one of the following is displayed:
The partition table format is identified by 'Partition table format' field. If the disk is MBR, a window similar to the left image is shown. GPT disks will have a window similar to the right image.