🚀 go-pugleaf

I'm writing a DLL which will be called by a visual basic program.
As part of its work, the DLL needs to modify a string which is owned
by the visual basic program.

For fairly intricate reasons, I cannot pass the string to the DLL as
a C-type (null terminated) string.  Instead I want to pass it as a standard
visual basic string.  That is, I do not want to pass the string with the 
ByVal keyword to my DLL.  Instead, I want to pass the string to my DLL in
the same way as I would pass it to a normal visual basic subroutine.
Unfortunately I need to know how visual basic stores its strings if I
am to do this.

I was wondering if anyone knows if there is a reference describing the format
of strings in visual basic.  Are there any ftp sites containing this info,
or do I have to buy the Visual Basic Control Development Kit?

Reply by eMail, and I'll summarise.  Thanks in advance,
Adrian.