6. As an exception to the Sections above, you may also compile
or link a "work that uses the Library" with the Library to
produce a work containing portions of the Library, and distribute
that work under terms of your choice, provided that the terms
permit modification of the work for the customer's own use and
reverse engineering for debugging such modifications.
[NOTE: This language is much more restrictive than it may appear.
The reverse engineering is allowed ONLY for debugging
modifications to the library. There is nothing to imply that
allowing reverse engineering extends to your work, so your
protection remains intact.]
You must give prominent notice with each copy of the work that
the Library is used in it and that the Library and its use are
covered by this License. You must supply a copy of this
License. If the work during execution displays copyright
notices, you must include the copyright notice for the Library
among them, as well as a reference directing the user to the copy
of this License. Also, you must do one of these things:
[Several options for supplying access to the library, and object
code for using modified libraries.]
<<<< END EXCERPT >>>>
My interpretation of all this is that you can pretty much protect
your commercial software. You need to acknowledge that you are
using V, and provide access to V. This can easily be accomplished
by providing a link to the V Web site.
Possibly the most objectionable part requires that you allow
users to relink the work using a modified version of V. This
provision can be satisfied by providing access to the the object
code files only upon request. You are also allowed to charge for
that access. Between these, I don't think there is much real
impact on using V for a commercial package.
So, by my interpretation, you can comply with the GNU license by
doing the following:
1. Acknowledge the use of V, and supply a reference to the
V Web site.
2. Supply a copy of the GNU LIBRARY GENERAL PUBLIC LICENSE.
The license implies that the object code is available for
relinking for an appropriate charge. I don't think you
need to explicitly state this anywhere else. You can also
make it clear that only the V library uses that GNU
LIBRARY GENERAL PUBLIC LICENSE, and that your commercial
software uses a different license.
3. Being prepared for the very unlikely event someone will
actually want to pay for access to the object code to
relink to a modified version of V.