As described in "Adding Designing a Layout Control" on page 380, the sample application's Rental Agreements Layout Control enables and disables fields on the Rental Agreements form to provide users with a visual indicator of the current phase of a Rental Agreement and what fields are currently available for editing.

The sample application defines three phases for a Rental Agreement:

• Check-Out: This is applicable to new records. When checking out a vehicle, only the Check-Out related fields are applicable. The Check-In related fields cannot be modified. See Form in Check-Out Phase.
• Check-In: Once a vehicle has been checked out, the Check-Out fields can no longer be modified and the Check-In fields are now available.  See Form in Check-In Phase.
• Complete: Once a vehicle has been checked in, the Rental Agreement is complete, and no additional changes can be made to either Check-Out or Check-In fields in the Rental Agreements record.  See Form in Complete Phase.

The validation to enforce a Rental Agreement's phase is defined in the Rental Agreements Entity Object. However, without the Layout Control, all fields on a Rental Agreements record would appear enabled regardless of the current phase of the rental agreement (as shown in Figure 14.94below). In this case, a user would not be notified of any validation errors until he or she attempts to save the record.
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RTF31303231373a204361707469Form Without Layout Control
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With the layout control linked to the Rental Agreements form, the set of available fields update automatically depending on the current phase of the Rental Agreement.

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_CheckOutPhase _CheckOutPhase

Form in Check-Out Phase

During a vehicle check-out, only the Check-Out fields are enabled on the new Rental Agreements record. Check-In fields are disabled, as shown in Figure 14below.95.
Check-Out Phase

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_CheckInPhase _CheckInPhase

Form in Check-In Phase

While a vehicle is checked out, only the Check-In fields are enabled on the Rental Agreements record (so the vehicle can be checked back in when returned). Check-Out fields are disabled, as shown in Figure 14.96.below.

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_CompletePhase _CompletePhase

Form in Complete Phase

While a vehicle has been returned and checked in, the details of the Rental Agreement can no longer be modified so all Check-In and Check-Out fields are disabled, as shown in Figure 14.97.
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