Some of the values used internally by Minecraft to generate worlds are exposed by CustomOreGen. These "properties" can be used by name in expressions as if they were variables. In that sense, they are similar to options. Unlike options, though, world and dimension properties are drawn from the Minecraft engine and are not set by COG.
Defining a config option with the same name as one of these properties will "hide" the property - the value of the option will be used instead. This can be exploited to override world properties for testing reasons or because the real values are not reliable (e.g. groundLevel).
World properties are common to an entire saved world (i.e. they are the same in all dimensions for that world).
|world||The world name, e.g. "New World".|
|world.seed||The world seed (a 64-bit integer).|
|world.version||The internal version number of the save file. As of Minecraft 1.4.2, the version for Anvil save files is 19133.|
|world.isHardcore||Whether or not hardcore mode is enabled.|
|world.hasFeatures||Whether or not terrain features (caves, strongholds, villages) are enabled.|
|world.hasCheats||Whether or not cheats are allowed by default.|
|world.gameMode||The default game mode. Values are "survival", "creative", and "adventure".|
|world.gameMode.id||The game mode ID number. Values are 0, 1, and 2, respectively.|
|world.type||The base world type. Values are "default", "flat", "largeBiomes", and "default_1_1".|
|world.nextRandom||A pseudorandom number in the range [0,1) based on the world seed. Although named like a world property to show that it depends on the current world, this is actually a function and it does return a different value each time it is used.|
Dimension properties are specific to a single dimension.
|dimension||"Overworld"||"Nether"||"The End"||The dimension name.|
|dimension.id||0||-1||1||The dimension ID. Each dimension in a given world has a unique ID which should remain the same so long as the world exists.|
|dimension.isSurface||True||False||False||Whether or not the dimension has a well-defined "surface" and a sky.|
|dimension.groundLevel|| 64 by default
4 for flat worlds
|same as overworld||50||Nominally, the ground level for surface dimensions. In practice, this property is not always reliable.|
|dimension.height||256||256||256||The maximum world height. This is always 256 for current Minecraft worlds, but it is possible that may change with mods or future versions.|
|dimension.generator|| "RandomLevelSource" by default
"FlatLevelSource" for flat worlds
|"HellRandomLevelSource"||"EndRandomLevelSource"||The generator used to create this dimension. This is an excellent way to tell the "type" of a dimension. Mod-added dimensions with unique landscapes (e.g. the Twighlight Forest) will have unique values for this property. Dimensions meant to resemble the overworld (e.g. Mystcraft ages) will use "RandomLevelSource".|
|dimension.generator.class|| "ChunkProviderGenerate" by default
"ChunkProviderFlat" for flat worlds
|"ChunkProviderHell"||"ChunkProviderEnd"||The underlying java class of the generator.|
|age||False||False||False||True if the the dimension is a Mystcraft age.|