I am thinking about how to handle boundary multipolygons and want get some feedback and ideas from you. There are two possible ways to use boundary information: 1. Draw the boundaries as lines 2. Draw the boundaries as polygons with different colours for different administrative levels I think the 2nd option cannot be realized (at the moment). I see no way how to define a style that differently colours adjoining polygons with rather identical tags (e.g. boundary=adminstrative, admin_level=2). So let's concentrate on the 1st option. One way may be part of different boundary relations. (admin_level=2 && admin_level=3 && admin_level=4 ....). To be able to process all of them with the style system the way must be duplicated for each relation. The multipolygon handling of boundaries might work as follows: For all ways (role=outer and inner) part of the boundary relation - Clone the original way - Tag the cloned way with the boundary information of the mp - Remove all tags from the original way that are also contained in the mp (with the same value) - Split all closed ways (polygons) in two ways to ensure that only ways are tagged with the boundary information What do you think? If no one really complains I will start implementing this (and expect that it will be accepted when I am ready :-). In case other multipolygon type also require such a processing we might add a config file in future which types are handled in this way. So this is ready to be more generic. WanMil