}
\references{
Maddison, D. R., Swofford, D. L. and Maddison, W. P. (1997) NEXUS: an
extensible file format for systematic information. \emph{Systematic
Biology}, \bold{46}, 590--621.
}
}
\references{
Maddison, D. R., Swofford, D. L. and Maddison, W. P. (1997) NEXUS: an
extensible file format for systematic information. \emph{Systematic
Biology}, \bold{46}, 590--621.
}