\Header{sQuote}{Quote Text}
\alias{dQuote}{sQuote}
\keyword{character}{sQuote}
\begin{Description}\relax
Single or double quote text by combining with appropriate single or
double left and right quotation marks.
\end{Description}
\begin{Usage}
\begin{verbatim}
sQuote(x)
dQuote(x)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x}] an \R{} object, to be coerced to a character vector.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
The purpose of the functions is to provide a simple means of markup
for quoting text to be used in the R output, e.g., in warnings or
error messages.

The choice of the appropriate quotation marks depends on both the
locale and the available character sets.  Older Unix/X11 fonts
displayed the grave accent (0x60) and the apostrophe (0x27) in a way
that they could also be used as matching open and close single
quotation marks.  Using modern fonts, or non-Unix systems, these
characters no longer produce matching glyphs.  Unicode provides left
and right single quotation mark characters (U+2018 and U+2019); if
Unicode cannot be assumed, it seems reasonable to use the apostrophe
as an undirectional single quotation mark.

Similarly, Unicode has left and right double quotation mark characters
(U+201C and U+201D); if only ASCII's typewriter characteristics can be
employed, than the ASCII quotation mark (0x22) should be used as both
the left and right double quotation mark.

\code{sQuote} and \code{dQuote} currently only provide undirectional
ASCII quotation style, but may be enhanced in the future.
\end{Details}
\begin{References}\relax
Markus Kuhn, \dQuote{ASCII and Unicode quotation marks}.
\url{http://www.cl.cam.ac.uk/~mgk25/ucs/quotes.html}
\end{References}
\begin{Examples}
\begin{ExampleCode}
paste("argument", sQuote("x"), "must be non-zero")
\end{ExampleCode}
\end{Examples}

