There are roads that could be classified by multiple street types. We think of ring roads (R-roads) which sometimes can also be a N-road categorized as Major Highway. For example, the ring road of Leuven, the R23, has long segments which are also N2 or N3. In these cases we categorize the ring road as Major Highway.
Ring roads which are also freeways, like the R0 of Brussels, are categorized as Freeway.