>
> 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