Undefined index and variables

Hi to all Being new to PHP I am naturally experiencing some minor problems. I have a form which processes Ref and Chassis data, when I load Add.php which does work but on loading get errors Notice: Undefined index: Ref in C:\Xitami\webpages\add.php on line 22 Notice: Undefined index: Chassis in C:\Xitami\webpages\add.php on line 23 How do I get rid of these undefined errors? Could anyone advise please. Regards Fred printf("<FORM action=\"add.php\" METHOD=post>"); printf("<TABLE border=\"0\" width=\"100%%\">"); printf("<TR><TD>Reference:</TD>"); printf("<TD><INPUT TYPE=text SIZE=5 NAME=Ref ></TD></TR>"); printf("<TR><TD>Chassis:</TD>"); printf("<TD><INPUT TYPE=text SIZE=25 NAME=Chassis ></TD></TR>"); printf("</TABLE>"); printf("<INPUT TYPE=submit name=\"submit\">"); printf("</FORM>" );