I've just hit an interesting situation for the first time.
I wrote a new program several months ago in VB.Net. Now, I have to update a legacy Visual Basic 6 program and need some routines from that VB.Net program.
There has been a lot of attention on how to best convert from VB6 to VB.Net, but now I am facing the opposite situation. I have to believe that this will be more common as time goes on, as legacy code can take a long time to truly fade away.
I know I can use COM Interop to use the VB.Net code directly from VB6, but I don't want to require that the .Net Framework be installed for users of the VB6 application. The best solution is modify the code to work in VB6. It's going to be interesting, I'll keep you posted...