6.32.4 Tab Sequence and Defaults
When you place components on a form, set the tab sequence of the components carefully, so that the user can move around the window using the Tab key.
In cases where the user is likely to choose one of the controls more often than the others, make it the default. For controls like radio buttons, check boxes and fields this is done using the tab sequence. For a push-button, this is done using the BtnDefault property.