Alexander, The discussion is drifting away somewhat ... So, the claim is that there's no need of explicit permission (in the Boost License) to make copies and copies of derived work (=distribute), because this right is granted by the USC. As a side note proprietary licenses do not allow distribution by explicitly forbidding it and are without doubt enforceable by virtue of being contracts. As another side note ditribution terms of GPL is not enforceable (in some cases) because one can legally obtain copies of GPL'ed software without being bound by the GPL and thus USC provisions apply. Are these yours and Boost lawers claims or have I misunderstood something ? And as another side note, when one is capable of downloading some software, does that mean that the software is in the public domain, just because one has no idea whether it has or has no rights to download it ? ~velco