@@ -27,7 +27,13 @@ MeshType = itk.Mesh[PixelType, Dimension]
 mesh = MeshType.New()
 
 # Create Vector Container and Store values in it for each Point
-v = itk.VectorContainer[itk.UL, PixelType].New()
+# For windows use itk.ULL
+if hasattr(itk.VectorContainer, 'ULAD'):
+    IdentifierType = itk.UL
+else:
+    IdentifierType = itk.ULL
+
+v = itk.VectorContainer[IdentifierType, PixelType].New()
 v.Reserve(NumberOfPoints)
 
 for i in range(NumberOfPoints):
# ==========================================================================
#
#   Copyright NumFOCUS
#
#   Licensed under the Apache License, Version 2.0 (the "License");
#   you may not use this file except in compliance with the License.
#   You may obtain a copy of the License at
#
#          http://www.apache.org/licenses/LICENSE-2.0.txt
#
#   Unless required by applicable law or agreed to in writing, software
#   distributed under the License is distributed on an "AS IS" BASIS,
#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#   See the License for the specific language governing permissions and
#   limitations under the License.
#
# ==========================================================================*/
import itk
import numpy as np

Dimension = 3
PixelType = itk.Array.D
NumberOfPoints = 10
PixelDataSize = 5

MeshType = itk.Mesh[PixelType, Dimension]
mesh = MeshType.New()

# Create Vector Container and Store values in it for each Point
v = itk.VectorContainer[itk.UL, PixelType].New()
v.Reserve(NumberOfPoints)

for i in range(NumberOfPoints):
    pixel_data_reference = v.CreateElementAt(i)
    pixel_data_reference.SetSize(PixelDataSize)
    pixel_data_reference.Fill(0)
    pixel_data_reference[0] = i
    pixel_data_reference[4] = i+4

# Set the point data container
mesh.SetPointData(v)

assert mesh.GetPointData().Size() == NumberOfPoints
assert mesh.GetPointData().ElementAt(0)[0] == 0
assert mesh.GetPointData().ElementAt(0)[4] == 4
assert mesh.GetPointData().ElementAt(2)[0] == 2+0
assert mesh.GetPointData().ElementAt(2)[4] == 2+4

# resize the PixelDataSize to see if it can be altered succesfully
PixelDataSize = 10
for i in range(NumberOfPoints):
    pixel_data_reference = v.CreateElementAt(i)
    pixel_data_reference.SetSize(PixelDataSize)
    pixel_data_reference.Fill(0)
    pixel_data_reference[0] = i
    pixel_data_reference[9] = i+10

assert mesh.GetPointData().Size() == NumberOfPoints
assert mesh.GetPointData().ElementAt(0)[0] == 0
assert mesh.GetPointData().ElementAt(0)[9] == 10
assert mesh.GetPointData().ElementAt(2)[0] == 2+0
assert mesh.GetPointData().ElementAt(2)[9] == 2+10

A generic way to check for Windows is `if os.name == 'nt'`. But if the one you wrote here works, we should keep it.