When you start a new project in EM.Tempo, a default-type domain is automatically created with a default offset value set equal to a quarter free-space wavelength (0.25λ<sub>0</sub>). As soon as you draw your first object, a blue domain box shows up in the project workspace and encloses your object. As you add more objects and increase the overall size of your structure, the domain box grows accordingly to encompass your entire physical structure. When you delete objects from the project workspace, the domain box also shrinks accordingly.
[[Image:FDTD14.png|thumb|370px350px|[[FDTD Module]]'s Domain Settings dialog.]]
===Changing the Domain Settings===