This error occurs when no description name is given for Local modifier.
Ensure that all statements used in the code are completed.
Example
[#Menu: Gateway of Tally]
Add: Item: "My Report": Display : MyReport
[Report: MyReport]
Use : DayBook
Local:Form
In the above example the form name is not specified. Hence the message error T0016: The description name is mandatory for the dynamic modifier Local.
The code is corrected by adding appropriate Form Name and required values for Local modifier.
[#Menu: Gateway of Tally]
Add: Item: "My Report": Display : MyReport
[Report: MyReport]
Use : DayBook
Local: Form: Daybook: Background: White