Gradients are complex modifiers for use in Mystcraft Ages. A gradient is a sequence of Colors, each with a Length. When used, the color displayed will change over time, as specified by the symbols that went into the gradient. Gradients are used by many of the Visual symbols, and also by the symbols Lightning, Normal Stars, Twinkling Stars, and Sunset Color.
Each step is defined by one Gradient symbol and its Color and Length modifiers. That is to say, when the Grammar is parsing a book, it will have at most one gradient, one color, and one length value active at a time. Each Gradient symbol will take all three of these, and replace them with a new gradient, adding the new color and length to the end. If there was no gradient, the color and length values will become the first step of a new gradient. If there was no color or length for a Gradient symbol, a random value will be supplied. After being taken by a Gradient, the length and color values will be considered "unset".
If there is no active gradient when one is called for, a color value can be promoted to a single-step gradient. This will also use any current length value, but in any case a single-step gradient looks like a constant color.