https://help.tallysolutions.com/docs/td9rel54/tdl_reference/release_6_0.htm

TDL Enhancements in Release 6

This page includes information on all the important TDL improvements made in Tally.ERP 9 Release 6.

Preprocessor Directive - InUse : Currently, when a TDL project is compiled in Tally.Developer 9 with Analyse option set in its properties, the analyser validates the entire code and identifies errors, warnings and remarks only from the statically used definitions. If definitions are used dynamically at runtime, the analyzer cannot determine the use of such definitions. In Release 6, with the help of the preprocessor directive InUse , you can identify the definitions which are used dynamically in the TDL code.

ActionEx : A new attribute ActionEx is provided to enhance the multi-action support at button or key level.

Do If : The action Do If is enhanced to support conditional action execution in TDL definitions like button.

To know the changes in Default Invoices refer the updates in Simple Printed Invoice , Comprehensive Invoice , POS Invoice , and Schema to support GST features in Tally.ERP 9.