function date (form){
var serial=form.inputbox.value;
prefix=serial.substr(0,1)
if (prefix=="A"){
prefix=serial.substr(0,2)}

if(prefix<=0)
	{message="That was an invalid serial number";year="";}
else{
message="Your Marlin 336 was manufactured in ";
if(prefix=="E")
	{year=1948;}
else{
if(prefix=="F")
	{year=1949;}
else{
if(prefix=="G")
	{year=1950;}
else{
if(prefix=="H")
	{year=1951;}
else{
if(prefix=="J")
	{year=1952;}
else{
if(prefix=="K")
	{year=1953;}
else{
if(prefix=="L")
	{year=1954;}
else{
if(prefix=="M")
	{year=1955;}
else{
if(prefix=="N")
	{year=1956;}
else{
if(prefix=="P")
	{year="early 1957";}
else{
if(prefix=="R")
	{year="late 1957 or early 1958";}
else{
if(prefix=="S")
	{year="late 1958 or 1959";}
else{
if(prefix=="T")
	{year="early 1960";}
else{
if(prefix=="U")
	{year="late 1960 or early 1961";}
else{
if(prefix=="V")
	{year="late 1961 or 1962";}
else{
if(prefix=="W")
	{year=1963;}
else{
if(prefix=="Y")
	{year="early 1964";}
else{
if(prefix=="Z")
	{year="late 1964";}
else{
if(prefix=="AA")
	{year=1965;}
else{
if(prefix=="AB")
	{year=1966;}
else{
if(prefix=="AC")
	{year=1967;}
else{
if(prefix=="AD")
	{year=1968;}
else{
if(prefix.substr(0,1)=="A" && parseInt(prefix.substr(1,1))==NaN)
	{message="Your Marlin 336 was manufactured after 1968";year="";}
else{message="That was an invalid serial number";year="";}
}}}}}}}}}}}}}}}}}}}}}}}
alert (message + year + ".");
}