There are three approaches to migrate the Formatter component.
If you want to use the old Formatter, you need to migrate the configuration that is related to the Formatter in the file dse.ini in BTT version 5.2 to the file btt.xml in BTT version 6.1 and keep all the other code the same as before.
If you want to use the new Formatter, you leverage the new features provided by the new Formatter component. Fist of all, you must migrate all the implemented FormatElement that extends from com.ibm.btt.base.FormatElement or its subclasses. You need to rewrite the FormatElement to make it extends from com.ibm.btt.format.CompositeFormat, com.ibm.btt.format.FieldFormat, or com.ibm.btt.format.BaseDecorator. Then, you must change the method call from FormatElement.format(DataElement)/FormatElement.format(Context) or FormatElement.unformat(DataElement)/FormatElement.unformat(Context) to com.ibm.btt.format.FormatElement.format(ReadAdapter) or com.ibm.btt.format.FormatElement.unformat(WriteAdapter).
If you have the old Formatter and the new one coexist in the system, you leverage the new features provided by the new Formatter, while keeping the existing code not modified. For detailed information, see Integrating with other BTT components.