Peter Spellucci, author of donlp2, has asked that netlib no longer
distribute donlp2, and says that donlp2 is still available as
ftp://ftp.mathematik.tu-darmstadt.de/pub/department/software/opti/DONLP2

Here is the former opt/index entry for donlp2:

lib	opt/donlp2
for	general differentiable nonlinear programming using dense linear algebra
by	Peter Spellucci
ref	see donlp2doc.txt, secqp.ps, and newregqp.ps (all in opt/donlp2)
prec	double
lang	Fortran 77 with milstd1753 extensions (include; do/enddo)
alg	sequential equality constrained quadratic programming with
,	regularized full QP in case of rank defiency of active constraints
gams	g2h3b1b