After you create a Description, you can add primitives to specified locations using the Specify Points Tool . 
You can use this method for all Description types. 
Add primitives using the Specify Points Tool
- In the XGen Editor, click the Primitives tab. 
- In the Generator Attributes section, set Generate Primitives one of the following: - 
Randomly across the surface
- 
At specified locations
 
- In the Primitives Attributes section, turn on More Primitives at, and then click Specify Points. 
- Use the Specify Points Tool to place point markers at the locations you want the primitives to generate. 
- Click Save &Close. When you preview the Description, primitives generate at the specified locations.