== Building the Physical Structure in EM.Tempo ==
[[Image:FDTD1.png|thumb|250px|[[FDTD Module]]'s Navigation Tree.]]
Your physical structure in EM.Tempo can be made up of several geometric objects with different material compositions. EM.Tempo groups your geometric objects in the project workspace based on their material type. All the objects belonging to the same material group share the same color and same material properties. EM.Tempo's material types are divided into seven categories:
Under each material node in the navigation tree, you can create new material groups of the same type but with different properties such as color, texture, or electric and magnetic constitutive parameters. These material groups are used to organize both the geometric objects you draw in the project workspace and those you import from external CAD model files.
[[Image:Info_icon.png|40px]] Click here to learn more about '''[[Defining_Materials_in_EM.Cube#Defining_a_New_Material_Group | Defining a New Material Group]]'''. Once a new material node has been created on the navigation tree, it becomes the "Active" material group of the project workspace, which is always listed in bold letters. When you draw a new CAD geometric object such as a Box box or a Spheresphere, it its name is inserted added under the currently active material type. There is only one material group that is active at any time. Any material can be made active by right clicking on its name in the Navigation Tree navigation tree and selecting the '''Activate''' item of the contextual menu. It is recommended that you first create material groups, and then draw new objects under the active material group. However, if you start a new EM.Tempo project from scratch, and start drawing a new object without having previously defined any material groups, a new default PEC group is created and added to the navigation tree to hold your new CAD object.
[[Image:Info_icon.png|40px]] Click here to learn more about '''[[Defining_Materials_in_EM.Cube#Moving_Objects_among_Material_Groups | Moving Objects among Material Groups]]'''.
{{Note|You can import external objects only to '''[[CubeCAD]]'''. You can then move the imported objects form [[CubeCAD]] to EM.Tempo.}}
[[Image:Info_icon.png|40px]] Click here for a general discussion of '''[[Defining Materials in EM.Cube]]'''.
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[[Image:FDTD_MAN1.png|thumb|left|250px|EM.Tempo's navigation tree.]]
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===Geometrical Rules & Material Hierarchy===