An object of class cross. See
read.cross for details.
filestem
A character string giving the first part of the output
file names (the bit before the dot).
chr
A vector specifying for which chromosomes data should be
written.
digits
Number of digits to which phenotype values should be
rounded.
Value
Data is written to a comma-delimited file, "filestem.csv",
where "filestem" is to be replaced by the corresponding
argument to the function. See read.cross.csv for a
description of the format.