The average value. Used as the value for the property itself.
How far away from the mean the values generated by the
property can be, as a fraction of the mean value.
Optionalseed: TypeMap.PropertyValue[T]A seed or set of seeds for the random number generator to use to generate the random property values. Leave this empty if you want a random seed. See randomSeed if you want a random seed and to link multiple values together.
Creates a property with a RandomFractionModifier and a mean value, effectively creating a property with a random values around a mean based on a fraction of that mean value.