Based on Wikipedia, for Thailand, I believe the country should be split into the following systems:
1) Thailand primary national roads: Single-digit and double-digit routes.
2) Thailand regional national roads: Triple-digit routes.
3) Thailand intra-regional roads: 4-digit routes <-- I'm not sure if this would be allowed in Travel Mapping since, well, it is the lowest national classification and there appears to be a very large number of them on Wikipedia, however, there is a lower classification than 4-digit routes, Rural Highways, which are overseen by a different department from the national roads.
4) Bangkok Expressway Network: These tolled expressways, and are owned and maintained by EXAT, a government enterprise. There's also the Don Muang Tollway which isn't owned or operated by EXAT, and is also not part of the national network, so I don't know where that would go.
5) Thai motorway network?: There are only two actual motorways in Thailand, and in Thailand, motorways are not classified as the same as Bangkok's Expressways. It's Route 7 which is a full motorway, and Route 9, only a part of which is a motorway. Since there's so few, perhaps this would just be included in the Thai Primary network?
Anyways, take this with a grain of salt, as I've never actually lived in, nor visited Thailand.