Integration differences between v3,v5&v6

Hi all
Have an application integrated with TT3 currently and want to upgrade to TT6. Primarily the app uses Itinerary files created from the app to fire up TT and provide navigation.
Can anyone outline the differences, from an integration perspective, between the three Navigator versions. For example, I know the itinerary file location is different between v3 and v6, but are there any other changes e.g. file formats?
Thanks for any help / suggestions - finding it difficult to get answers from TT Pro....
Cheers
VT

I can't answer your question directly but there is a free programme named ITNConv which allows you to covert itineraries saved with AutoRoute into TT. With a bit of experimenting you may find the answer.

http://benichougps.blogspot.com/ the site is FRench but the download is English.

You go go here http://benitools.info/itnconv.zip to go straight to the download.