If data exists on all elements in the definition part then data can be created for the new element. Data is constructed for, or attached to, the newly constructed element according to the scheme shown in Figure 6.3, which summarises both the issues involved and the actions taken in various circumstances. In general it is possible (1) to construct data from the elements and data carriers referred to in the definition part, and (2) if the element already existed beforehand, for the replacing element to adopt the data already attached beforehand. The default action is governed by the builddata control. The program handles any necessary conversions from data carriers defined using the FACTOR: command. Recall that components might also possess data, and this will be incorporated as appropriate.
Figure 6.3: Automatically attaching data to constructed elements