What does a VMAX device configuration of "PE" mean?

I ran across this and it has stumped everyone I've asked.

C:\Users\Administrator>symdev -sid 590 show 27bf

    Device Physical Name     : Not Visible

    Device Symmetrix Name    : 027BF
    Device Serial ID         : N/A
    Symmetrix ID             : 000196700590

    Number of RAID Groups    : 0
    Encapsulated Device      : No
    Encapsulated WWN         : N/A
    Encapsulated Device Flags: None

    Encapsulated Array ID    : N/A
    Encapsulated Device Name : N/A
    Attached BCV Device      : N/A

    Attached VDEV TGT Device : N/A

    Vendor ID                : EMC
    Product ID               : SYMMETRIX
    Product Revision         : 5977
    Device WWN               : 600009700BB969AE22C100CE00000000
    Device Emulation Type    : FBA
    Device Defined Label Type: N/A
    Device Defined Label     : N/A
    Device Sub System Id     : 0xFFFF
    Cache Partition Name     : N/A

    Device Block Size        : 512

    Device Capacity
        {
        Cylinders            :            2
        Tracks               :           30
        512-byte Blocks      :         7680
        MegaBytes            :            4
        KiloBytes            :         3840

        Geometry Limited     : No
        }

    Device External Identity
        {
        Device WWN           : 600009700BB969AE22C100CE00000000

        Front Director Paths (0): N/A

        Geometry             : Native
            {
            Sectors/Track        :          256
            Tracks/Cylinder      :           15
            Cylinders            :            2
            512-byte Blocks      :         7680
            MegaBytes            :            4
            KiloBytes            :         3840
            }
        }

    Device Configuration     : PE
            
    SCSI-3 Persistent Reserve: Enabled

    Dynamic Spare Invoked    : No

    Dynamic RDF Capability   : None

    STAR Mode                : No
    STAR Recovery Capability : None
    STAR Recovery State      : NA
    SQAR_MODE                : No

    Device Service State     : Normal

    Device Status            : Ready            (RW)
    Device SA Status         : N/A              (N/A)
    Device User Pinned       : False
    Host Access Mode         : Active
    Device Tag(s)            : None

    Extent Based Clone       : None
    Snapvx Source            : False
    Snapvx Target            : False
    Data Destaged            : True
    DIF1 Flag                : False
    Gatekeeper Device        : True
    AS400_GK                 : False
    Host Cache Registered    : False
    Optimized Read Miss      : N/A

    Mirror Set Type          : [Thin,N/A,N/A,N/A]

    Mirror Set DA Status     : [RW,N/A,N/A,N/A]

    Mirror Set Inv. Tracks   : [0,0,0,0]

    Mirror Configuration Information
        {
        Mirror Number                          : 1
        Mirror Type                            : Thin
        Mirror Status                          : Ready           (RW)
        }