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The main difference between these two types of geometry definition is that only the Design Space is categorized as a space. A space get the additional information regarding the material of the geometry. Whereas masks are just marking areas in the Design Space such as Non-Design Spaces, Constraints, Forces etc. by adding attributes explained below. For every creation of a Non-Design Space or another boundary condition a new Mask is being created. However, if you simultaneously select multiple cells in the Non-Design Space Tool and then create the Non-Design Space all cells are saved in just one Mask. This creation and handling of the Masks is very important for the Keep Non-Design Spaces Function.
Example: Generative Design - Bookshelf
The Bookshelf is a beginner tutorial with just a few Non-Design Spaces and boundary conditions. Thus, it is a great example to explain and to have a look at the different geometries. It has one Design Space, four Non-Design Spaces, one Mask representing the force application area and three Masks representing the fixation application area. The Space and Masks are marked in the picture below.
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