Unit Editor dialog box

Use the Unit Editor dialog box to create and delete Unit definitions for your model.

To open this dialog box, use one of the following methods:

Default Unit Definitions

This displays a list of the Unit definitions that are built into Stella. These are commonly used units that are included for your convenience. The Unit Name appears first, followed by the Unit Equation, and Unit Aliases in parentheses. If you create a unit definition that would be in conflict with any built in definition the definition will be removed as described in To Create New Units from Scratch.

My Unit Definitions

This displays a list of the Unit definitions you've created. These are applied to every model you work with. To edit one of these, click on it to open the editing controls. To delete, click on the at the right.

Model Specific Unit Definitions

This displays a list of the Unit definitions contained only in the model. You can create these specifically. They may also appear in models you get from other people; unit definitions in this category may have been in the My Units category of the model author. To edit one of these, click to open the editing controls. To delete, click on the at the right.

You can move a Unit definition from My Units to Model Specific Units by clicking on it, then clicking on the Add to Model Specific button. Conversely, You can move a Unit definition from Model Specific Unit Definitions to My Unit definitions by clicking on it, then clicking on the Add to My Unit Definitions button.

Note: If you remove a Unit definition from My Unit Definitions, it won't be used in new models you create. If, however, it's used in a model not currently opened, it will still be used, but will be kept in the Model Specific Units list. If there are concurrently opened models in the same Stella session the definition will be removed from those as well.

For more information, see To Delete Units You've Created.

Unit Name

Type a unique name for the new unit of measure. The name can't be used by any other Unit definition in any category. The name must begin with a letter and contain only letters, numbers, and $. You can include spaces or underbars in the name interchangeably, with one or more of either being treated the same as a single space in comparing unit names (that is, a____b and a_b are considered the same when comparing units).

Unit Equation

Type the equation for the unit. If you leave the box blank, you must enter an alias. You can make a new unit equivalent to an existing unit by entering the existing unit name (whereas using the name in your unit name or an alias will remove the existing unit definition).

For more information about creating equations, see Creating Equations for Units.

Unit Alias

Enter a comma separated list of equivalent names for the Unit you're defining. This list can be empty if you've specified an equation, but one of an equation or an alias is required. If you simply want to use a name for a unit of measure, enter it directly in the Units entry for the model variable; you don't need to define it first.

Add to My Unit Definitions

Click this button to add the new unit of measure to the "My Units" list. The entries you've made will be validated when you do this.

Add to Model Specific Unit Definitions

Click this button to add the new unit of measure to the "Model Specific Units" list. The entries you've made will be validated when you do this.