function validate_field(field,alerttxt) {
  with (field) {
    if (value==null||value=="") {alert("please provide " + alerttxt); field.focus();return false;}
    else {return true;}
  }
}

function validate_email(field,alerttxt) {
  with (field) {
    apos=value.indexOf("@");
    dotpos=value.lastIndexOf(".");
    if (apos<1||dotpos-apos<2) {alert(alerttxt);  field.focus();return false;}
    else {return true;}
  }
}

function validate_form(thisform) {
  with (thisform) {
     if (!validate_field(registrant,"the name of the person completing the form")) {return false;}
     if (!validate_field(heading,"the heading for your site")) {return false;}
     if (!validate_email(email,"Please ensure your email address is valid")) {return false;}
     if (!validate_field(suburb,"the suburb for your listing")) {return false;}
     if (!validate_field(name,"the name of the deceased")) {return false;}
     if (!validate_field(charity1,"at least one donation recipient organisation")) {return false;}
     if (!validate_field(message,"a brief message for your site")) {return false;}
  }
}