A model in Tetra is used to store all the information related to a decision. This includes the alternatives, criteria, weights and ratings. In Tetra GDM, the model includes weights and ratings from all of the decision makers involved.

Models are managed differently in Tetra SDM and GDM, as dicussed here.

Tetra SDM Models

In Tetra SDM, models are stored as files on your computer. You may save your changes at any point and, conversly, if you quit or close the model without saving, any changes will be lost.

Tetra GDM Models

In Tetra GDM, models are stored in a database. To create or delete models the Tetra GDM Administration Tool must be used. Once a model is created, the model owner may provide access to other users by creating other decision makers. In order to work with a model, a user must be able to access the database (either through a local area network, or over the internet). Unlike Tetra SDM, as changes are made to the model, these changes are saved automatically and continuously to the database. This means that you don't have to worry about periodically saving the model, but it also means that if you want to keep a copy of an earlier version of a model you must export the model and then import it into a new, empty model. Note that as you change settings on rulers, these are only saved in the database when you save or close the ruler. If you quit or close the model without saving changes to rulers, these changes will be lost.


As you work on models in both SDM and GDM a log can be kept of changes made. You can turn on this option and specify a location for the log file to be stored, in the preferences dialog. When logging is enabled, you can view the log by choosing View Log... under the Model menu.

This section contains subsections on Working with Tetra SDM Model Files, Working with Tetra GDM Models, Importing and Exporting Models, Navigating Models and Working with Rulers.