Example Natives:

JASS:
native SetTerrainType takes real x, real y, integer terrainType, integer variation, integer area, integer shape returns nothing
native GetTerrainType takes real x, real y returns integer
Examples from TriggerData.txt
terrainshape=1,1,1,WESTRING_TRIGTYPE_terrainshape,integer
terraintype=1,1,1,WESTRING_TRIGTYPE_terraintype,integer
// Tile IDs
TerrainTypeLdrt=1,terraintype,'Ldrt',WESTRING_TERRAINTYPE_Ldrt
TerrainTypeLdro=1,terraintype,'Ldro',WESTRING_TERRAINTYPE_Ldro
And a lot more.
SetTerrainTypeBJ=1,location,terraintype,integer,integer,terrainshape
_SetTerrainTypeBJ_Defaults=GetRectCenter,TerrainTypeLdrt,-1,1,TerrainShapeCircle
_SetTerrainTypeBJ_Category=TC_ENVIRONMENT