Creating and deleting unit definitions

If the units you want to assign are not in the list of available units, you can create a new unit of measure from scratch or by basing it on one or more existing units. You can also simply type in the units you want to use as a name or an equation involving names.

Tip: You can choose to make units you create in one model available for all of your models or create them only for the current model.

The following procedures describe how to use the Unit Editor dialog box to create new unit definitions from scratch, how to create new unit definitions by deriving them from other definitions, and how to delete unit definisions you have created.

To create new unit definitions

  1. Open the Unit Editor dialog box by using one of these methods:

    The Unit Editor dialog box opens.

    The available unit definitions are divided into three sections: Default Units, My Units and Model Specific Units. All can be used within the current model, and you can add definitions to My Units or Model Specific Units. To add a unit definition:

  2. In the Unit Name box, type a unique name for the new unit of measure. This name will appear in the shortcut menu used to assign units and autocomplete will also prompt you with it.

  3. In the Unit Equation box, type the equation for the new unit of measure. If you leave the box blank, the software assumes that the unit of measure's name and equation are the same. If you want to create an additional alias for an existing unit definition type in that unit for the equation. For more information about creating equations, see Creating equations for units.

  4. In the Unit Alias box, optionally type in a comma separated list of equivalent names for the unit you are defining. For example the unit Cans might have aliases Can, Tin Can, Tin Cans.
  5. When you are finished specifying the new unit definition, click Add To My Units or click Add To Model Specific UnitsThe new unit of measure definition is added to the corresponding list in alphabetical order. Assigning the named unit, any of its aliases, or its equation to a variable will have the meaning.

To derive units from existing units

  1. Open the Unit Editor dialog box by using one of these methods:

    The Unit Editor dialog box opens.

  2. In the "Available Units" list, select the existing unit of measure from which you want to derive the new unit of measure.

  3. Click Derive New Unit.

    The name, equation (if any) and short name (if any) for the selected unit of measure appear in the boxes at the bottom of the dialog box.

  4. Edit the name, equation, and short name for the new unit of measure.
  5. When you are finished specifying the new unit of measure, click Add To List.

To delete units you have created

You can delete Unit definitions that you have created or that are in a model you are working withby clicking on the black X next to the Unit in the appropriate list of the Unit Editor dialog box. You may also move unit definitions between being model specific and kept for all your models by clicking on the Unit in the list and clicking either the << or >> buttons.

If you delete Units definitions that are being used in the model, the equivalence they used to provide will no longer hold. For example if you had defined Días with equation Days and then removed it, the units Days and Días would no longer match.

Moving Unit definitions between My Units and Model Specific Units will have no effect on check Units results, whereas deleting definitions may. Removing Unit definitions from either category will have no effect on Check Unit results for other models: Unit definitions used in those models will simply change category according to the changes you make.

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