Visuals

Visual symbols affect only the appearance of the world, but not any gameplay factors. The category is required for an age description, and can appear many times. If no Visuals are specified, the grammar can insert a few.

Most of these are symbols which simply change the color of part of the environment. Each of these has a "Natural" version which takes no modifiers, and a "custom" version which takes a color (ground colors) or gradient (sky colors) as their only modifier. There are also a couple of extra sky effects. Note that sunset colors (including sunrise, moonset, moonrise) have their own symbol, while Stars and Lightning take their colors from a modifier.

All the color schemes default to the Overworld coloring. Specifying the same color scheme (e.g., Foliage Color) more than once in a book causes their respective color or gradient values to be combined in the usual fashion. This includes the "natural" versions, which allows mixing the the default colors with chosen colors. Example: "Natural Foliage Color, Red, Foliage Color, Natural Foliage Color" would put a reddish tint on the Overworld coloring.

Ground colors take only a color modifier (except Natural versions). The local biome can also affect the results, especially Swampland biomes. Naturally, if the affected blocks are moved to or from a different age (or biome, for that matter), they will change color as appropriate to their new location.
 * Foliage Color: Not all trees may be affected, notably mod trees.
 * Natural Foliage Color
 * Grass Color
 * Natural Grass Color
 * Water Color: Minecraft imposes a blue tint on water.  "White, Water color" will give the vanilla color, "Pink, Water color" will give a grayish color.
 * Natural Water Color

Sky Colors: The non-Natural symbols take a Gradient.
 * Fog Color: Affects both distance fading and "void fog".
 * Natural Fog Color
 * Cloud Color
 * Natural Cloud Color
 * Sky Color
 * Natural Sky Color
 * Night Sky Color: Shows when no sun is in the sky.
 * Natural Night Sky Color

Visual Effects:
 * Boundless Sky: No visible horizon, popular for void and island worlds.
 * Rainbow: A rainbow will show in the sky.  Takes Direction modifiers.