\name{xmlParamVal}
\alias{xmlParamVal}
\alias{xmlParamName}
\title{Translates Parameter Name string to XML}
\description{
  The function \code{xmlParamName} converts a parameter name string into
  a \code{<ParName>}, \code{<VarParName>} or \code{<StateParName>} XMLNode
  depending on the \code{pname} argument.

  The function \code{xmlParamVal} produces a 
  a \code{<ParameterValue>}, \code{<VarParameterValue>} or
  \code{<StateParameterValue>} XMLNode depending on the \code{pname}
  argument. 
}
\usage{
xmlParamVal(pname, pval)
xmlParamName(pname)
}
\arguments{
  \item{pname}{Name of the parameter, see details section.}
  \item{pval}{Value of the parameter}
}
\details{
  Parameter names can in one of three forms:
    (a) \emph{name} --- A scaler parameter called \emph{name}.
    (b) \emph{name}(\emph{var}) --- A variable parameter called
      \emph{name} for variable \emph{var}.
    (c) \emph{name}(\emph{var},\emph{state}) --- A state parameter called
      \emph{name} for state \emph{state} of variable \emph{var}.
   The three have different XML representations.
}
\value{
  An object of type \code{XMLNode}.
}
\references{
  \url{http://research.ets.org/~ralmond/StatShop/dataFormats.html}
}
\author{Russell Almond}
\seealso{
  \code{\link[XML]{XMLNode}}, \code{\link{xmlDistribution}},
  \code{\link{xmlParameterSet}}
}
\examples{
  pnnode <- xmlParamName("Task Difficulty")
  vpnnode <- xmlParamName("Relative Importance(Reading)")
  spnnode <- xmlParamName("Level Difficulty Increment(Outcome_R,Good)")

  pvnode <- xmlParamVal("Task Difficulty",1.0)
  vpvnode <- xmlParamVal("Relative Importance(Reading)",0.0)
  spvnode <- xmlParamVal("Level Difficulty Increment(Outcome_R,Good)",0.5)

  ## Expected values.
  pn1 <- "<ParName>Task Difficulty</ParName>"
  vpn1 <- "<VarParName varName=\"Reading\">Relative Importance</VarParName>"
  spn1 <- "<StateParName varName=\"Outcome_R\" state=\"Good\">Level Difficulty Increment</StateParName>"

  pv1 <- "<ParameterValue parameterName=\"Task Difficulty\">1</ParameterValue>"
  vpv1 <- "<VarParameterValue varName=\"Reading\" parameterName=\"Relative Importance\">0</VarParameterValue>"
  spv1 <- "<StateParameterValue varName=\"Outcome_R\" state=\"Good\" parameterName=\"Level Difficulty Increment\">0.5</StateParameterValue>"

  \dontshow{
   pn1n <- xmlRoot(xmlTreeParse(pn1))
   vpn1n <- xmlRoot(xmlTreeParse(vpn1))
   spn1n <- xmlRoot(xmlTreeParse(spn1))
   pv1n <- xmlRoot(xmlTreeParse(pv1))
   vpv1n <- xmlRoot(xmlTreeParse(vpv1))
   spv1n <- xmlRoot(xmlTreeParse(spv1))

   allexp <- list(pn1n,vpn1n,spn1n,pv1n,vpv1n,spv1n)
   allact <- list(pnnode,vpnnode,spnnode,pvnode,vpvnode,spvnode)

   stopifnot(
    identical(sapply(allexp,xmlName),sapply(allact,xmlName)),
    identical(sapply(allexp,xmlValue),sapply(allact,xmlValue)),
    identical(sapply(allexp,function(x) xmlGetAttr(x,"varName")),
              sapply(allact,function(x) xmlGetAttr(x,"varName"))),
    identical(sapply(allexp,function(x) xmlGetAttr(x,"state")),
              sapply(allact,function(x) xmlGetAttr(x,"state"))),
    identical(sapply(allexp,function(x) xmlGetAttr(x,"parameterName")),
              sapply(allact,function(x) xmlGetAttr(x,"parameterName")))
    )
  } 
}
\keyword{interface}