BOF offset 0-3, XML 1.0 declaration, then mandatory elements, ‘document’, ‘interlinear-text’, ‘paragraphs’– see https://github.com/sillsdev/FieldWorks/blob/develop/DistFiles/Language%20Explorer/Export%20Templates/Interlinear/FlexInterlinear.xsd. There are additional non-mandatory elements and attributes that can appear, which may mean that relative offsets between elements may need to be tweaked further.