levelplot.panel.levelplot(x, y, z, 
                subscripts,
                at = pretty(z),
                shrink,
                labels = NULL,
                label.style = c("mixed", "flat", "align"),
                contour = FALSE,
                region = TRUE,
                col = add.line$col,
                lty = add.line$lty,
                lwd = add.line$lwd,
                cex = add.text$cex,
                font = add.text$font,
                fontfamily = add.text$fontfamily,
                fontface = add.text$fontface,
                col.text = add.text$col,
                ...,
                col.regions = regions$col,
                alpha.regions = regions$alpha)
panel.contourplot(...)levelplot and
  contourplot (which differ only in default values of some
  arguments). panel.contourplot is a simple wrapper to
  panel.levelplot.  When contour=TRUE, the contourLines function is used to
  calculate the contour lines.
levelplot, contourLines