You have to take a look to the following posts:
- https://www.codeguru.com/vb/gen/vb_misc/userdefinedtypesudts/article.php/c5615/Understanding-UDTs.htm
- http://sandsprite.com/CodeStuff/SavingObjects-IN-vb.html
- http://www.vbforums.com/showthread.php?807205-VB6-pipe-based-UDT-serializing-deserializing-InMemory