\HeaderA{comment}{Query or Set a `Comment' Attribute}{comment}
\aliasA{comment<\Rdash}{comment}{comment<.Rdash.}
\keyword{attribute}{comment}
\begin{Description}\relax
These functions set and query a \emph{comment}
attribute for any \R{} objects.  This is typically useful for
\code{\LinkA{data.frame}{data.frame}}s or model fits.

Contrary to other \code{\LinkA{attributes}{attributes}}, the \code{comment} is not
printed (by \code{\LinkA{print}{print}} or \code{\LinkA{print.default}{print.default}}).

Assigning \code{NULL} or a zero-length character vector removes the
comment.
\end{Description}
\begin{Usage}
\begin{verbatim}
comment(x)
comment(x) <- value
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x}] any \R{} object
\item[\code{value}] a \code{character} vector, or \code{NULL}.
\end{ldescription}
\end{Arguments}
\begin{SeeAlso}\relax
\code{\LinkA{attributes}{attributes}} and \code{\LinkA{attr}{attr}} for other attributes.
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
x <- matrix(1:12, 3,4)
comment(x) <- c("This is my very important data from experiment #0234",
                "Jun 5, 1998")
x
comment(x)
\end{ExampleCode}
\end{Examples}

