Procedural terrains use nodes to define detail, rather than polygons, when Vue askes you if you want to add nodes when applying the terrain, it's asking if you want the materials bump pattern to physically modify the terrain node mapping or if you want Vue to add more nodes to the terrain to hold the way it appears before you apply the new material. In general I've found it's best to add nodes as I usually want the terrain to hold the shape I've got and not to be modified by the material I'm applying to it. Procedural terrains are still capable of being edited in the terrain editor (as they should), but because of the node based geometry that is new to only procedural terrains it would be very involved to add booleon operation capablitiy to a procedural terrain. Agiel pretty much summed it up, lots of mathematics behind the scenes. One other thing, you can still do it the way you did in Vue 4, but only with the standard terrains (I wasn't clear from your question if you thought Procedural terrains were the only ones available any more). Hope this all helps.