Thanks again my friend.

Thing I got that: A A6 string is a kind of char.

But I still don't understand the link between the string definiton and a char array. Why should I change my own struct definition to include char arrays instead of pure chars?

Additionally you mentioned another point. You wrote, I'll have to add my "own APIcalls for strcpy, strcat...".

First of all, just to see whether I really understand you: As A6's strings are something special and these functions expect not only a string but a special form, namely a "A6 string", they wouldn't work with a "normal" (that means a standard C) string.
Is that right?

But as I should deal with char-arrays (see above, I still don't get the why), I have to find a way to rewrite these functions to accept these inputs..?

To make things worse, I have no idea how to change the APIcalls as I don't even know how they look like. I'll have a look at the manual immediately, maybe there are some hints concerning these ominous calls, but just in the case I don't find something appropriate - in fact appropriate for me - how could I start here?

Phew. That's becoming real tough for me.