Dynamic Cell Access (DCA) controls the access levels for line items within modules. It is simple to implement and provides modelers with a flexible way of controlling user inputs. Here are a few tips and tricks to help you implement DCA effectively.
Any line item can be controlled by any other applicable Boolean line item. To avoid confusion over which line item(s) to use, it is recommended that you add a separate functional area and create specific modules to hold the driver line items. These modules should be named appropriately (e.g. Access – Customers > Products, or Access – Time etc.). The advantage of this approach is the access driver can be used for multiple line items or modules, and the calculation logic is in one place. In most cases, you will probably want read and write access. Therefore, within each module it is recommended that you add two line items (Write? and Read?). If the logic is being set for Write?, then set the formulas for the Read? line item to NOT WRITE? (or vice-versa). It may be necessary to add multiple line items to use for different target line items, but start with this a default.
You may not need to create a module that mirrors the dimensionality of the line item you wish to control. For example, if you have a line item dimensioned by customer, product, and time, and you wish to make actual months read-only, you can use an access module just dimensioned by time. Think about what dimension the control needs to apply to and create an access module accordingly.
There are three different states of access that can be applied: READ, WRITE, and INVISIBLE or hidden. There are two blueprint controls (read control and write control) and there are two states for a driver (TRUE or FALSE). The combination of these determines which state is applied to the line item. The following table illustrates the options:
|Read Access Driver|
|Target Line Item||READ||INVISIBLE|
|Write Access Driver|
|Target Line Item||WRITE||INVISIBLE|
|Read Access Driver||Write Access Driver|
|Target Line Item||READ||INVISIBLE||WRITE||Revert to Read*|
The settings can also be expressed in the following table:
|WRITE ACCESS DRIVER|
Note: If you want to have read and write access, it is necessary to set both access drivers within the module blueprint.
Think about how you want the totals to appear. When you create a Boolean line item, the default summary option is NONE. This means that if you used this access driver line item, any totals within the target would be invisible. In most cases, you will probably want the totals to be read-only, so setting the access driver line item summary to ANY will provide this setting. If you are using the Invisible setting to “hide” certain items and you do not want the end user to compute hidden values, then it is best to use the ANY setting for the access driver line item. This means that only if all values in the list are visible then the totals show; otherwise, the totals are hidden from view.