So it turns out copyright is a function of an external DLL.
It seems you need to have the correct .DLL and .decls file too. To identify the required dll you may search for a ".decls" file that contains the "copyright" function declaration. In the first line of this .decls file you can see the name of the dll. Copy the dll to your blitz sources folder and the decls file to the folder "userlibs" in the Blitz3D installation folder.
(Well, it seems to be this way if this function isn't part of the blitz sourcecode, which is what I assume.)
It seems you need to have the correct .DLL and .decls file too. To identify the required dll you may search for a ".decls" file that contains the "copyright" function declaration. In the first line of this .decls file you can see the name of the dll. Copy the dll to your blitz sources folder and the decls file to the folder "userlibs" in the Blitz3D installation folder.
(Well, it seems to be this way if this function isn't part of the blitz sourcecode, which is what I assume.)