open( OUTPUT, ">", "some.file" ) or die "$!";
print OUTPUT rm3dHeader();
print OUTPUT rm3dData();
close OUTPUT;

sub rm3dHeader
{
    return "START_OF_FILE\n\nDATEFORMAT=YYYYMMDD\nDECIMALSEPARATOR=.\n";
}

sub rm3dData
{
    return "this is the data\n";
}