Steps to be followed in order to migrate the code
TDLByte #11
Step 2
Generate Compatibility Metadata
This is a step where a tdlserver.ddif file is created in the Tally.ERP 9 folder. This file contains the information about the TDL definitions in the source code of the selected release.
(DDIF – Developer Description Index File).
  To generate this file, right click on the loaded default TDL of base release
and select 'Generate Compatibility Metadata' as shown below