As I wrote in http://tantek.com/2018/079/t2 (https://github.com/microformats/microformats2-parsing/issues/30#issuecomment-374784404), the 'type' array must not convey any ordering semantics from the source (thus it must enforce an artificial order that does not convey anything, in addition to uniqueness per set requirements). All other uses of arrays in the parsed JSON output (children, property values, rel subarrays) already convey appropriate document order semantics.