Hello (not sure what went wrong with first thread on this),

Tying to add a custom property to excel rows. My code seems to be correctly adding the xml as below.

<x:row>

....

<x:customProperties>

< x:customPr xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships" name="MyCustomProp" r:id="PropId" />

< /x:customProperties>

</x:row/>

And I've added a CustomPropertyPart with the property value and and Id="PropId". Despite CustomProperty being ECMA supported Excel 2010 removes the customproperty on savingas and in the productivity tool it reflects as an upsupported element:

OpenXmlUnknownElement openXmlUnknownElement1 = OpenXmlUnknownElement.CreateOpenXmlUnknownElement("<x:customProperties...

Is this expected behaviour? Is there another way I can persist a property on rows without excel deleting the data on saveas?

Thanks in advance?