Sum of the weights of the elements added or modified in a given version of a Model with respect to a previous one (e.g. an attribute of a class or a filter condition on an association role).
The increment of a Model version should not be confused with the difference between its weight and the weight of the previous version: the new version might weight the same or even less than the previous one, while it's increment might still be positive. For instance, the weight of the eliminated model elements can partially compensate or even exceed the weight of the added elements.
In other words, the weight of a Model can decrease from one version to the next one, while the increment of a Model version with respect to a previuous one is always by definition positive or at least zero.