Subforms are used to illustrate one-to-many relationships in forms. The main form and the subform are synchronized, which means that when you switch records in the main form, the subform displays the corresponding records for the “many” relationship. Figure 10-20 shows a form that displays product data. The subform displays the monthly sales figures for the respective product.
The subform’s control element properties Link Child Fields and Link Master Fields define the relationship between the main form and the subform, as displayed in Figure 10-21.