It's a question of parsing the data.
You (means mkgmap) have to rebuild superroutes, till there are only way-member in it.
Eg: parse tile and read all relation (maybe store in RAM) if relation_A contains relations_B, replace all relations_B in this relation_A with the objects the relation_B1...Bn contain. end, if no relation contains any relation.
This shouldn't be very complex and not very expensive, because there are typical not so many relation in one tile.
Yes, but mkgmap must make sure that it handles the case when relations are building loops: Examples: rel_a contains rel_b, rel_b contains rel_a or, a bit more complex: rel_a -> rel_b -> rel_c -> rel_d->rel_b some time ago I found a relation (probably a joke) like this: rel_a -> rel_a splitter handles this for the problem relations and it is not very time consuming. Gerd