Function try_export_landxml_terrain 

pub fn try_export_landxml_terrain(
    content: &[u8],
    product_ids: &[u32],
    options: &LandXmlTerrainOptions,
) -> Result<LandXmlTerrainExport, LandXmlTerrainRefusal>

Export the selected terrain products of content (IFC STEP bytes) as one LandXML 1.2 document, one <Surface> per product in selection order.

Fails closed with a LandXmlTerrainRefusal naming the first product or attribute that does not meet the contract; nothing partial is returned.