This section specifies the partition settings that are used. Note: the unattended install creates a hidden "System Reserve" with a size of 100MB and partition order of 1, therefore there is no "1" option in Partition Order because it is already in use. More info can be found here.
Wipe Disk specifies whether to erase all partitions and data on the hard disk before adding additional configurations to the disk. Wipe Disk is blocked in Windows PE if any of the following conditions are true:
Install to disk specifies the identification number of the disk on which to install Windows. Specifies the identification number of the disk on which to install Windows. Disk_identity_number is an integer. This is a relative 0-based index. Disks are numbered 0, 1, 2, and so on, in the order they are created, unless otherwise specified, by using this setting.
Main Partition Active specifies whether to mark the partition as active. On a BIOS-based system, the active partition is the partition the system will boot to. This partition must be a primary partition. On a Unified Extensible Firmware Interface (UEFI)-based system, this setting is not used. The system will always boot to the EFI System Partition (ESP). If Active is set for this partition type, it is ignored. Only one active partition can be set on a hard disk. If an active partition already exists on the disk when this setting is changed to true, the existing active setting is removed and the selected partition is marked as active. Only primary partitions can be marked as active. If Active is set for other partition types, the setting is ignored.
Main Partition Format specifies the file-system format to apply to the partition.
Main Partition Label specifies the name that you apply to a partition.
Main Partition Letter specifies a drive letter to assign to the partition.
Partition Order specifies the identification number of the partition to modify. The first partition on a disk has the value of 1, the second, 2, and so on. Because the partition structure on a disk can change during installation, it is important to be aware of the changes to the partitions on a disk as you are creating your unattended installation answer file. If you create additional partitions during Windows Setup, PartitionID must exactly match the partition that you modify. For example, if you add two logical partitions to your disk configuration and then modify the last partition, the partition ID of the last partition will have changed from 3 to 5.