OptionaldecimalsDecimal places in the written unit, 0 to 9. Default 6.
OptionallinearDefault 'metre'. 'usSurveyFoot' writes elevations in international
feet: LandXML 1.2 has no US-survey-foot elevation unit, and both units are
declared in <Units>.
OptionalnowHeader stamp (LandXML@date / @time, written in UTC). Default now.
OptionalsurfaceSurface@name per product express id; a blank name keeps the IFC name.
How the document is written (#7618); every field is optional.