# Xdfm file with mixed element topology

**URL:** https://discourse.paraview.org/t/xdfm-file-with-mixed-element-topology/15118
**Category:** ParaView Support
**Created:** [July 25, 2024, 8:59am UTC](https://discourse.paraview.org/t/xdfm-file-with-mixed-element-topology/15118 "2024-07-25T08:59:39Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![chemakm](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/c/46a35a/32.png) [@chemakm](https://discourse.paraview.org/u/chemakm)
#### Post date: [July 25, 2024, 8:59am UTC](https://discourse.paraview.org/t/xdfm-file-with-mixed-element-topology/15118/1 "2024-07-25T08:59:39Z")

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Hi,

I have a question about opening mixed topology saved in Xdmf format in Paraview.

I am writing the the attribues in HDF files (.h5) and the I genetrate also the .xmf file. As I have a grid with different types of elements, I used the TopologyType=“Mixed”. Here’s a simple example with 2 elements, one triangle and one quad, written in XML format:

```auto
<Topology TopologyType="Mixed" NumberOfElements="2">
      <DataItem Format="XML" DataType="Int" Dimensions="9">
            4 0 1 4
            5 0 1 5 3
      </DataItem>
</Topology>

```

It works fine when the elements are written in XML Format, but I have more than 100,000 elements which results in huge .xmf files. I want to store these elements also in HDF format with Variable Length arrays (see below), but Paraview craches when it opens the file.

![image](https://discourse.paraview.org/uploads/default/original/2X/e/ea4c7f37d1f3bc45c5cbbf86a431491735d884f2.png)

Is there any way to efficiently store girds with mixed topologies in Xdmf format ?

Thanks.