This is very interesting, on another thread we had someone ask about the GPL and modifications to GPL'd software. I looked at the GNU FAQ on the subject, located at http://www.gnu.org/licenses/gpl-faq.html.
It clearly states
The GPL does not require you to release your modified version. You are free to make modifications and use them privately, without ever
releasing them. This applies to organizations (including companies), too; an organization can make a modified version and use it internally without ever releasing it outside the organization.
But if you release the modified version to the public in some way, the GPL requires you to make the modified source code available to the users, under the GPL.
Thus, the GPL gives permission to release the modified program in certain ways, and not in other ways; but the decision of whether to release it is up to you.
If ACS4.6 is a modified version of GPL software, is seems like it must be released as GPL as well. aD may be in violation of the GPL.
