Field help (KALWCOD5) 

Help common to the single and mass process for the account posting change. 
When the Update indicator is set to Yes, this field displays the specific rule code defined by the field associations.
This code can only be entered or modified if the Process indicator is activated for the plan and if the Update field is set to Yes.
The rule to apply is selected according to the depreciation mode selected and/or the depreciation plan. For example, rules generating fiscal help (Help 25 %, Help 50 %, Energy, Depreciation rise 30 %, ...) can only be applied for the Fiscal plan.

Note on the 40% deduction [15/04/15-14/04/17] Specific rule for a French company:

To apply this rule, the purchase date must be on or before 14/04/17. If not, you receive the message "If the specific rule no longer applies at the purchase date, make sure you have the rights to apply it. Do you confirm?" You can select Yes or No to dismiss the message.

Yes: Applies the rule even if the purchase date is past 14/04/17.

No: Creation or updates are not applied and you need to change the Specific rule to None or cancel the action.