diff --git a/src/ome_autogen.py b/src/ome_autogen.py
index beef7a62..d7c327e6 100644
--- a/src/ome_autogen.py
+++ b/src/ome_autogen.py
@@ -985,8 +985,8 @@ def _simple_class(self) -> List[str]:
         if self.type.local_name == "Hex40":
             return [
                 "class Hex40(ConstrainedStr):",
-                "    min_length = 20",
-                "    max_length = 20",
+                "    min_length = 40",
+                "    max_length = 40",
             ]
 
         lines = []
diff --git a/testing/data/fake-plate-rows-2.ome.xml b/testing/data/fake-plate-rows-2.ome.xml
new file mode 100644
index 00000000..4945aa05
--- /dev/null
+++ b/testing/data/fake-plate-rows-2.ome.xml
@@ -0,0 +1 @@
+<?xml version="1.0" encoding="UTF-8"?><OME xmlns="http://www.openmicroscopy.org/Schemas/OME/2016-06" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openmicroscopy.org/Schemas/OME/2016-06 http://www.openmicroscopy.org/Schemas/OME/2016-06/ome.xsd"><Experiment ID="Experiment:0" Type="Photobleaching"><Description>Experiment</Description></Experiment><Plate ColumnNamingConvention="number" Columns="1" ExternalIdentifier="External Identifier" ID="Plate:0" Name="Plate Name 0" RowNamingConvention="letter" Rows="2" Status="Plate status" WellOriginX="0.0" WellOriginXUnit="µm" WellOriginY="1.0" WellOriginYUnit="µm"><Description>Plate 0 of 1</Description><Well Color="255" Column="0" ExternalDescription="External Description" ExternalIdentifier="External Identifier" ID="Well:0_0_0_0" Row="0" Type="Transfection: done"><WellSample ID="WellSample:0_0_0_0_0_0" Index="0" PositionX="0.0" PositionXUnit="reference frame" PositionY="1.0" PositionYUnit="reference frame" Timepoint="2006-05-04T18:13:51"><ImageRef ID="Image:0"/></WellSample></Well><Well Color="255" Column="0" ExternalDescription="External Description" ExternalIdentifier="External Identifier" ID="Well:0_0_1_0" Row="1" Type="Transfection: done"><WellSample ID="WellSample:0_0_1_0_0_0" Index="1" PositionX="0.0" PositionXUnit="reference frame" PositionY="1.0" PositionYUnit="reference frame" Timepoint="2006-05-04T18:13:51"><ImageRef ID="Image:1"/></WellSample></Well><PlateAcquisition EndTime="2006-05-04T18:13:51" ID="PlateAcquisition:0" Name="PlateAcquisition Name 0" StartTime="2006-05-04T18:13:51"><Description>PlateAcquisition 0 of 1</Description><WellSampleRef ID="WellSample:0_0_0_0_0_0"/><WellSampleRef ID="WellSample:0_0_1_0_0_0"/></PlateAcquisition></Plate><Instrument ID="Instrument:0"><Microscope LotNumber="9876543210" Manufacturer="Manufacturer" Model="Model" SerialNumber="0123456789" Type="Upright"/><Laser FrequencyMultiplication="30" ID="LightSource:0" LaserMedium="Alexandrite" LotNumber="9876543210" Manufacturer="Manufacturer" Model="Model" PockelCell="false" Power="200.0" PowerUnit="mW" RepetitionRate="30.0" RepetitionRateUnit="aHz" SerialNumber="0123456789" Tuneable="false" Type="Dye" Wavelength="200.0" WavelengthUnit="nm"/><Arc ID="LightSource:1" LotNumber="9876543210" Manufacturer="Manufacturer" Model="Model" Power="200.0" PowerUnit="mW" SerialNumber="0123456789" Type="HgXe"/><Filament ID="LightSource:2" LotNumber="9876543210" Manufacturer="Manufacturer" Model="Model" Power="200.0" PowerUnit="mW" SerialNumber="0123456789" Type="Halogen"/><LightEmittingDiode ID="LightSource:3" LotNumber="9876543210" Manufacturer="Manufacturer" Model="Model" Power="200.0" PowerUnit="mW" SerialNumber="0123456789"/><Laser FrequencyMultiplication="30" ID="LightSource:4" LaserMedium="Alexandrite" LotNumber="9876543210" Manufacturer="Manufacturer" Model="Model" PockelCell="false" Power="200.0" PowerUnit="mW" RepetitionRate="30.0" RepetitionRateUnit="aHz" SerialNumber="0123456789" Tuneable="false" Type="Dye" Wavelength="200.0" WavelengthUnit="nm"/><Detector AmplificationGain="0.0" Gain="1.0" ID="Detector:0" LotNumber="9876543210" Manufacturer="Manufacturer" Model="Model" Offset="2.0" SerialNumber="0123456789" Type="CCD" Voltage="100" VoltageUnit="V" Zoom="3.0"/><Objective CalibratedMagnification="1.0" Correction="UV" ID="Objective:0" Immersion="Oil" Iris="true" LensNA="0.5" LotNumber="9876543210" Manufacturer="Manufacturer" Model="Model" NominalMagnification="1.5" SerialNumber="0123456789" WorkingDistance="1.0" WorkingDistanceUnit="µm"/><FilterSet ID="FilterSet:0" LotNumber="9876543210" Manufacturer="Manufacturer" Model="Model" SerialNumber="0123456789"/><Filter ID="Filter:0" LotNumber="9876543210" Manufacturer="Manufacturer" Model="Model" SerialNumber="0123456789" Type="LongPass"><TransmittanceRange CutIn="200.0" CutInTolerance="1.0" CutInToleranceUnit="nm" CutInUnit="nm" CutOut="300.0" CutOutTolerance="1.0" CutOutToleranceUnit="nm" CutOutUnit="nm" Transmittance="0.5"/></Filter><Filter ID="Filter:1" LotNumber="9876543210" Manufacturer="Manufacturer" Model="Model" SerialNumber="0123456789" Type="LongPass"><TransmittanceRange CutIn="200.0" CutInTolerance="1.0" CutInToleranceUnit="nm" CutInUnit="nm" CutOut="300.0" CutOutTolerance="1.0" CutOutToleranceUnit="nm" CutOutUnit="nm" Transmittance="0.5"/></Filter><Dichroic ID="Dichroic:0" LotNumber="9876543210" Manufacturer="Manufacturer" Model="Model" SerialNumber="0123456789"/></Instrument><Image ID="Image:0" Name="my"><Description>Image Description 0</Description><ExperimentRef ID="Experiment:0"/><ImagingEnvironment AirPressure="1.0" AirPressureUnit="mbar" CO2Percent="1.0" Humidity="1.0" Temperature="1.0" TemperatureUnit="°C"/><StageLabel Name="StageLabel" X="1.0" XUnit="reference frame" Y="1.0" YUnit="reference frame" Z="1.0" ZUnit="reference frame"/><Pixels BigEndian="true" DimensionOrder="XYZCT" ID="Pixels:0" Interleaved="false" PhysicalSizeX="1" PhysicalSizeXUnit="µm" PhysicalSizeY="1" PhysicalSizeYUnit="µm" PhysicalSizeZ="1" PhysicalSizeZUnit="µm" SignificantBits="8" SizeC="1" SizeT="1" SizeX="512" SizeY="512" SizeZ="1" Type="uint8"><Channel AcquisitionMode="FluorescenceLifetime" Color="1687603455" ContrastMethod="Brightfield" EmissionWavelength="300.3" EmissionWavelengthUnit="nm" ExcitationWavelength="400.3" ExcitationWavelengthUnit="nm" Fluor="Fluor" ID="Channel:0:0" IlluminationType="Oblique" NDFilter="1.0" Name="Name" PinholeSize="0.5" PinholeSizeUnit="µm" PockelCellSetting="0" SamplesPerPixel="1"><LightSourceSettings Attenuation="1.0" ID="LightSource:0" Wavelength="200.2" WavelengthUnit="nm"/><DetectorSettings Binning="2x2" Gain="1.0" ID="Detector:0" Integration="20" Offset="1.0" ReadOutRate="1.0" ReadOutRateUnit="Hz" Voltage="1.0" VoltageUnit="V" Zoom="3.0"/><LightPath><ExcitationFilterRef ID="Filter:1"/><DichroicRef ID="Dichroic:0"/><EmissionFilterRef ID="Filter:0"/></LightPath></Channel><MetadataOnly/><Plane DeltaT="0.1" DeltaTUnit="s" ExposureTime="10.0" ExposureTimeUnit="s" PositionX="1.0" PositionXUnit="reference frame" PositionY="1.0" PositionYUnit="reference frame" PositionZ="1.0" PositionZUnit="reference frame" TheC="0" TheT="0" TheZ="0"><HashSHA1>1234567890ABCDEF1234567890ABCDEF12345678</HashSHA1></Plane></Pixels></Image><Image ID="Image:1" Name="my 2"><Description>Image Description 1</Description><ExperimentRef ID="Experiment:0"/><ImagingEnvironment AirPressure="1.0" AirPressureUnit="mbar" CO2Percent="1.0" Humidity="1.0" Temperature="1.0" TemperatureUnit="°C"/><StageLabel Name="StageLabel" X="1.0" XUnit="reference frame" Y="1.0" YUnit="reference frame" Z="1.0" ZUnit="reference frame"/><Pixels BigEndian="true" DimensionOrder="XYZCT" ID="Pixels:1" Interleaved="false" PhysicalSizeX="1" PhysicalSizeXUnit="µm" PhysicalSizeY="1" PhysicalSizeYUnit="µm" PhysicalSizeZ="1" PhysicalSizeZUnit="µm" SignificantBits="8" SizeC="1" SizeT="1" SizeX="512" SizeY="512" SizeZ="1" Type="uint8"><Channel AcquisitionMode="FluorescenceLifetime" Color="1687603455" ContrastMethod="Brightfield" EmissionWavelength="300.3" EmissionWavelengthUnit="nm" ExcitationWavelength="400.3" ExcitationWavelengthUnit="nm" Fluor="Fluor" ID="Channel:1:0" IlluminationType="Oblique" NDFilter="1.0" Name="Name" PinholeSize="0.5" PinholeSizeUnit="µm" PockelCellSetting="0" SamplesPerPixel="1"><LightSourceSettings Attenuation="1.0" ID="LightSource:0" Wavelength="200.2" WavelengthUnit="nm"/><DetectorSettings Binning="2x2" Gain="1.0" ID="Detector:0" Integration="20" Offset="1.0" ReadOutRate="1.0" ReadOutRateUnit="Hz" Voltage="1.0" VoltageUnit="V" Zoom="3.0"/><LightPath><ExcitationFilterRef ID="Filter:1"/><DichroicRef ID="Dichroic:0"/><EmissionFilterRef ID="Filter:0"/></LightPath></Channel><MetadataOnly/><Plane DeltaT="0.1" DeltaTUnit="s" ExposureTime="10.0" ExposureTimeUnit="s" PositionX="1.0" PositionXUnit="reference frame" PositionY="1.0" PositionYUnit="reference frame" PositionZ="1.0" PositionZUnit="reference frame" TheC="0" TheT="0" TheZ="0"><HashSHA1>1234567890ABCDEF1234567890ABCDEF12345678</HashSHA1></Plane></Pixels></Image></OME>
\ No newline at end of file