Associative spaces are bounded by objects that define the space area. If the boundary objects change, the space inside them is updated, too. You will typically work with associative spaces when entering the documentation phase of the project.
Associative spaces can be 2D spaces, extruded 3D spaces, or 3D freeform spaces. An associative 2D or extruded 3D space is associative only to the objects in the X and Y direction of the floor plan. The height is either 0 or a user-defined extrusion height. A 3D freeform space is associative to the objects bounding it in all 3 spatial dimensions.
Spaces can be associative to many 3D and linework objects.
A space can be associative to boundary objects in external references. If the boundary objects in the external reference change, the space in the host drawing changes, too. However, spaces that have been generated in an external reference do not interact with boundary objects in the host drawing.