This item is selectable if you have more than one open scenario. It enables users to transfer substance data from a different scenario. By picking a substance it is easy to create a scenario with a substance that, for several reasons, was once edited but not stored in the database (e.g. experimental parameter modifications, invalid parameter set).
Cancelling the dialog will return you to the previous state.
If you select a substance, the modified state of the current scenario substance is checked. If it is modified, a confirmation dialog will ask you either to save the current substance data (see Save Substance, Section 1.2.6) or not. The only way to avoid the replaceing of the substance related to the active scenario is to reject an existing data set being overwritten in the substance database.