Masking regions provide a way to obscure elements in a view.
Masking regions may be useful in scenarios like the following: -
You need to obscure elements in a project. - You are creating a
detail family or a model family and need the background of the
element to mask the model and other detail components when it is
loaded into a project. - You need to create a model family (from
imported 2D DWG files) that obscures other elements when placed
in a view. You can create 2D and 3D masking regions. 2D masking
regions can be created in a project and in the Family Editor
when you are creating a 2D family (annotation, detail, or title
block). 3D masking regions can be created in the Family Editor
when you are creating a model family. Masking regions do not
participate in shading; they are always drawn the background
color of the drawing area. Masking regions cannot be applied to
element subcategories. Exporting Masking Regions to DWG When you
export a project or family that contains a masking region, any
lines that