This flag applies only to checkboxes, in which case it causes the initial field value to be loaded from the current state of the existing checkbox (assuming there is an existing checkbox control at the specified coordinates) rather than the entry parameter. This helps deal with the fact that clicking on a checkbox (even when it is not currently under the control of INFLD) may toggle the value of the checkbox (in addition to sending the keyboard string associated with the field). If your app responded to the resulting exitcode by calling INFLD to edit the clicked-on checkbox, the app's copy of the checkbox's value (stored from the previous time it was edited with INFLD) may be out of sync with the new actual state of the checkbox, in which case it would appear to the user that it sometimes takes two clicks to get the checkbox to change value.
This is equivalent to setting type ||b.
