<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><br class=""><blockquote type="cite" class="">On Nov 12, 2019, at 10:26 AM, Joseph Eisenberg <<a href="mailto:joseph.eisenberg@gmail.com" class="">joseph.eisenberg@gmail.com</a>> wrote:<br class=""><br class="">If you are mapping an area, as in this case, just use a closed way or multipolygon.<br class=""></blockquote><br class="">How would a closed way (area polygon) denote “top” and “Bottom”? <br class=""><br class="">if embankments can be easily expressed as a single simple polygon, how data users infer “top” and "bottom” from that is beyond me. <br class=""><br class="">That is the issue: I don’t understand how a polygon would represent that, and I think those two different pieces of mapping need to be explicitly tagged. <br class=""><br class="">Perhaps it is because while I have 3000+ edits, I rarely use relations or other complex mapping data structures, nor understand exactly what data consumers can infer from data vs what they need explicitly tagged to be useful (as I am not a data user) - but I assume that “top” and "Bottom” are difficult to infer, as slope data needs to be explicitly tagged to ways. <br class=""><br class="">I thought that the way (man_made=embankment [top]) + a polygon to represent the bank (area:man_made=embankment) would, together, represent the top and the area of the embankment, allowing inference of the direction of the slope. Perhaps an additional line for “bottom” would be necessary too. <br class=""><br class="">Two embankments would represent the slopes of the levee, while the man_made=dyke way would represent the path of the protection structure as a whole, as the embankments (particularly the outer one) are not continuous - but the levee (as a complete structure) is continuous. <br class=""><br class=""><br class="">Javbw</body></html>