\Header{terms.formula}{A function to construct a terms object from a formula.}
\keyword{models}{terms.formula}
\begin{Description}\relax
This function takes a formula and some optional arguments and
constructs a terms object. The terms object can then be used to
construct a \code{\Link{model.matrix}}.\end{Description}
\begin{Usage}
\begin{verbatim}
terms.formula(x, specials=NULL, abb=NULL, data=NULL, neg.out=TRUE,
              keep.order=FALSE, ...)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x}] A formula.
\item[\code{specials}] What functions in the formula should be marked as
special in the terms object.
\item[\code{abb}] Unused in R.
\item[\code{data}] A data frame from which the meaning of the special symbol
\code{.} can be inferred. It is unused if there is no \code{.} in
the formula.
\item[\code{neg.out}] \code{TRUE} if terms with a minus, \code{-} should be
removed. If FALSE these are kept in and indicate a negative order
(for fractionate?).
\item[\code{keep.order}] A logical value indicating whether the terms should
keep their positions. If FALSE the terms are reordered so that main
effects come first.
\item[\code{...}] further arguments passed to or from other methods.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
Not all of the options work in the same way that they do in S and not
all are implemented.\end{Details}
\begin{Value}
A \code{\Link{terms}} object is returned.\end{Value}
\begin{SeeAlso}\relax
\code{\Link{terms.object}},  \code{\Link{terms.default}}\end{SeeAlso}

