$ cat vm.xml
<?xml version="1.0" encoding="UTF-8"?>
<wxm:VirtualMachines xmlns:wxm="urn:com.io7m.waxmill.vm:1:0">
    <wxm:VirtualMachine id="538a90e4-d50d-4511-8643-ae418279bac4" name="com.io7m.example">
        <wxm:CPUTopology sockets="1" threads="1" cores="1"/>
        <wxm:Memory gigabytes="0" megabytes="250"/>
        <wxm:Devices>
            <wxm:HostBridge vendor="UNSPECIFIED">
                <wxm:DeviceSlot bus="0" slot="0" function="0"/>
            </wxm:HostBridge>
            <wxm:AHCIDiskDevice>
                <wxm:DeviceSlot bus="0" slot="1" function="0"/>
                <wxm:StorageBackendZFSVolume/>
            </wxm:AHCIDiskDevice>
            <wxm:AHCIOpticalDiskDevice>
                <wxm:DeviceSlot bus="0" slot="2" function="0"/>
            </wxm:AHCIOpticalDiskDevice>
            <wxm:VirtioNetworkDevice>
                <wxm:DeviceSlot bus="0" slot="4" function="0"/>
                <wxm:TAPDevice name="tap23" address="a3:26:9c:74:79:34"/>
            </wxm:VirtioNetworkDevice>
        </wxm:Devices>
        <wxm:BootConfigurations>
            <wxm:BootConfigurationGRUBBhyve name="run">
                <wxm:GRUBBhyveKernelOpenBSD>
                    <wxm:BSDBootDevice kernelPath="/bsd">
                        <wxm:DeviceSlot bus="0" slot="2" function="0"/>
                    </wxm:BSDBootDevice>
                </wxm:GRUBBhyveKernelOpenBSD>
            </wxm:BootConfigurationGRUBBhyve>
        </wxm:BootConfigurations>
        <wxm:Flags>
            <wxm:Flag name="DisableMPTableGeneration" enabled="false"/>
            <wxm:Flag name="ForceVirtualIOPCIToUseMSI" enabled="false"/>
            <wxm:Flag name="GenerateACPITables" enabled="true"/>
            <wxm:Flag name="GuestAPICIsX2APIC" enabled="false"/>
            <wxm:Flag name="IncludeGuestMemoryInCoreFiles" enabled="false"/>
            <wxm:Flag name="RealTimeClockIsUTC" enabled="false"/>
            <wxm:Flag name="WireGuestMemory" enabled="false"/>
            <wxm:Flag name="ExitCPUOnPAUSE" enabled="true"/>
            <wxm:Flag name="YieldCPUOnHLT" enabled="true"/>
        </wxm:Flags>
    </wxm:VirtualMachine>
</wxm:VirtualMachines>

$ waxmill vm-import --file vm.xml
INFO com.io7m.waxmill.cmdline.internal.WXMCommandVMImport: Imported 1 virtual machines

$ waxmill vm-import --file vm.xml
ERROR com.io7m.waxmill.cmdline.Main: com.io7m.waxmill.exceptions.WXMExceptionDuplicate: A virtual machine already exists with the given ID.
  ID:                  538a90e4-d50d-4511-8643-ae418279bac4
  Machine (A) Name:    com.io7m.example
  Machine (A) Source:  file:///tmp/vm.xml
  Machine (B) Name:    com.io7m.example
  Machine (B) Source:  file:///etc/waxmill/vm/538a90e4-d50d-4511-8643-ae418279bac4.wvmx
