Software distributed by netlib comes with the disclaimer that ``anything free comes with no guarantee''. In contrast to commercial vendors like NAG and IMSL, netlib offers no support beyond whatever documentation contributing authors choose to provide with their code. These caveats also apply to xnetlib.
On the other hand, both netlib and xnetlib provide free, easy access to a large body of high-quality code, and the phenomenal growth of netlib and xnetlib attests to the value of this service. We hope that xnetlib, by making high-quality code even more accessible, will encourage software developers to make their codes freely available and will make good programming easier for the scientific computing community.