New Jalview release -- hesitating on license

[Pierre Gruet <pgtdebian@free.fr>]

Hi,

I'm stumbling upon the license terms of a part of the code (which is 
important enough so that the whole program really needs it) of the new 
release of Jalview I am packaging: that part has a license identical to 
BSD-3-clause except that clause 3 bas been changed to:

   3. Redistributions must acknowledge that this software was
      originally developed by the UCSF Computer Graphics Laboratory
      under support by the NIH National Center for Research Resources,
      grant P41-RR01081.

I'm really doubting this can be seen as DFSG-free:
- "acknowledge" seems vague to me;
- it looks like someone could be sued if he made a derived work without 
a sentence about the original developer and the grant number.

Maybe you have a definitive answer? Else should I write to 
debian-legal@lists.debian.org or to FTPmasters ?


Thanks a lot for your support in any case,

Best regards,
Pierre