This error occurs when the developer is trying to modify an internal description.
%s :%s - Description Type : Description Name.
Do not attempt to modify internal descriptions. Use the description, if necessary.
Example
[#Report: ePayments]
In the above code, the report ePayments is an internal fixed description. Hence the message error T0010: Could not modify the fixed description Report: ePayments. appears.
The error is corrected by defining a new definition to use the fixed description as given below:
[Report: TSPLePayments]
Use: ePayments
