Managing User-Defined Units

There are two kinds of user-defined units:

• Units that are stored in your system units file, and hence are available to any model that you edit on your computer. The system units file A file on your hard drive (named units.dat) that stores all of your unit settings. (units.dat) is located in an application data subfolder on your computer (the location of this file differs depending on the operating system). That is, these units are stored separately on your computer (i.e., not just in the model file itself). These are highlighted in red font in the Units Manager, and are referred to here as system units (since they are stored with your system - the computer).
• Units that are only stored within the model file itself, and are not available to any other models that you edit on your computer. These are highlighted in bold red in the Units Manager, and are referred to here as model units (since they are only stored with the model).

Any unit that you create on your computer automatically becomes a system unit (i.e., it is stored in the system units file, and hence is subsequently available to any other model you open on your computer.

Whenever a file is saved, any user-defined units that it uses are saved with the file. Therefore, if you open a file that contains user-defined units created by someone else, these units will be available in the file (as model units). They will not, however, become part of your system units file. That is, they do not become system units and are only local to that model. Hence, they would appear in the Units Manager when viewing that file (and marked as bold red).

Note: If you open a model with a user-defined model unit, and the same unit is defined as a system unit on your computer (but has a different definition), GoldSim will display a warning message. The model unit will be ignored and the system unit will be applied for that model (which could cause some expressions to become invalid).

If you have opened a file with a model unit, and you would like to convert this to a system unit (so it is available to other models that you open or create), you can do so as follows:

1. Open the Units Manager.
2. Find the unit and click on it.
3. Click through the Wizard until you press Finish.
4. The unit will then become a system unit.

If you want to delete a system unit from you computer (so it is no longer available to other models you open or create), you can do so as follows:

1. Open the Units Manager.
2. Find the unit and select it.
3. Press the Remove button.
4. If the unit does not exist in the current file, it will immediately be removed from the Units Manager (and hence will no longer be a system unit). If the unit does exist in the current file, it will be converted from a system unit to a model unit.

When managing user-defined units, you must take care when copying portions of a model that utilize user-defined units between files:

• If you copy a portion of one model which references a user-defined unit to a second model which does not have that unit, you will need to create the unit in the second model (since otherwise it will not recognize the unit).
• If you copy a portion of one model which has a user-defined unit to a second model which has the same user-defined unit with a different definition, the definition of the unit in the second (destination) model will be used in the combined model, and this may result in an incorrect calculation or an invalid expression.