All Plateaus and Highlands (World)

This group collects the 19 Landforms subcategory members that the atlas already places under its own Plateaus and Highlands subcategory, the whole real-world population the atlas covers there. It is a single flat group, not split further by region or country, because Plateaus and Highlands stays well under ruling 926's own hundred-member threshold for a further split (the largest sibling landform type subcategory in this pass, still under 100 members). It sits directly under the Plateaus and Highlands subcategory (in-subcategory) and under the atlas's own Groups category (in-category), giving a reader a direct browse path from either the Plateaus and Highlands subcategory page or the Groups index. SourceId is intentionally NULL on both the group-to-subcategory edge and every member's own in-group edge below: the underlying classification already lives on each member's own live Plateaus and Highlands subcategory placement, a fact already recorded and sourced when the member itself was minted; filing it under this atlas's own browse structure is an organizational fact about the atlas, not a new claim about the world, the same convention w-groups-build-0922 and w-groups-group-geography3-0923 already established for this identical shape of write.