This option is used for assigning a material to some selected entities.
When working in geometry mode, the kind of entity to which you wish to assign a material must be selected, i.e. point, line, surface or volume; when working in mesh mode, you select directly the elements to which the material is to be assigned.
Note: A material cannot be applied over nodes; a material only assigned to points will be transferred to 1-node elements if generated, but not to nodes themselves.
If assigning from the command line, the UnAssignMat option erases all the assignments of a particular material.
Caution: Once a mesh has been generated, any changes made to the assigned materials require you to regenerate the mesh or reassign these materials directly to the mesh.