Hi - Thank you for your patience! I was able to get feature classes based on the referenced xml copy/pasting correctly by making a few minor changes:Add the Shape_Length field to the fieldset for the feature class:<Field xsi:type="esri:Field">
<Name>Shape_Length</Name>
<Type>esriFieldTypeDouble</Type>
<IsNullable>true</IsNullable>
<Length>8</Length>
<Precision>0</Precision>
<Scale>0</Scale>
<Required>true</Required>
<Editable>false</Editable>
<AliasName>Shape_Length</AliasName>
<ModelName>Shape_Length</ModelName>
</Field>
Then I added information on what the area and length field names are between the <HasSpatialIndex /> and <Extent /> tags. Note that there is no Shape_Area, but the empty tag needs to be there:<HasSpatialIndex>true</HasSpatialIndex>
<AreaFieldName/>
<LengthFieldName>Shape_Length</LengthFieldName>
<Extent xsi:nil="true"/>
Finally I changed the CLSID from<CLSID>{86E3C61F-7D4E-48DF-8B2E-AF71CD0BCB61}</CLSID>
to<CLSID>{52353152-891A-11D0-BEC6-00805F7C4268}</CLSID>
Hope this gets you past this hurdle!