You can use expressions to generate values for modifier attributes, masks and regions maps. For example, you can create an expression that randomizes the cut amount of a Cut modifier or the amount of curl a Clump modifier applies to hairs.
 Attributes that are controllable by expressions have these icons 
		 ,
, 
		 in the 
		Attribute Editor as they are also controllable by texture files and painted textures.
 in the 
		Attribute Editor as they are also controllable by texture files and painted textures. 
	 
For example, for a Cut modifier connect it to the Amount attribute.


See XGen Expression Editor for more information about loading and editing expressions.