A function with bindings for legend, col, lty, lwd, ncol, and .... This latter function takes as arguments x and y, the coordinates for the location of the legend on the plot, and it adds the legend to the current plot.
References
S. Dudoit and Y. H. Yang. (2002). Bioconductor R packages for exploratory analysis and normalization of cDNA microarray data. In G. Parmigiani, E. S. Garrett, R. A. Irizarry and S. L. Zeger, editors, The Analysis of Gene Expression Data: Methods and Software, Springer, New York.