AWK IF ELSE block

nawk -F"," ' BEGIN{OFS=","} {if (NR==1) {
print "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXx"
} else {
print $1,$2,$3,$4,"S",1
print $1,$2,$3,$5,"S",2
print $1,$2,$3,$6,"D",1
print $1,$2,$3,$7,"D",2
}}' in.txt