Suppose you have already modelled an object type Journey, which is identified by a journey code, and which already plays several roles in other fact types. But you now want to change the identification of this object type because the journey code is expanded with a country code and the year in which it takes place.
If you were to delete the object type Journey, all facts related to Journey would be deleted as well and it would require you to model all this information again. Below is described a simpler and faster way to resolve this.
First we'll rename the existing Journey to Journey Old (this enables us to insert the new Journey object type, since CaseTalk doesn't allow duplicate names). Right-click to activate the context menu in the diagram and select IG Tasks \ Rename.
Now we'll enter the new expression that represents the new identification structure, including the journey code, the country code and the year. Press F6 to enter a new expression and enter the expression Journey FR021999, making sure you select the "Create OTE" checkbox. Qualify the expression like this:
Before we can replace the Journey Old, we have to make sure the population has the same number of tuples. Therefore we select Edit Population either in our context menu in the diagram or using the context menu on the expressions in the IG window. We add FR031999 and FR011999 to the population. Our diagram now looks like this:
We can now replace Journey Old. Use the context menu in the IG Window on Journey Old and select Replace in the menu. From the list, we choose object type Journey. The following dialog will appear to confirm this action:
If we now look at the diagram we'll see that the model is correct and contains an object type Journey with the new identification: