function checkDate(d,m,y)
  { // Checks for valid date in range 1/1/1900 to 31/12/2099
    if (!isNumeric(d) || !isNumeric(m) || !isNumeric(y)) {return false;}
        if (m<1 || m>12) {return false;}
        if (y<1900 || y>2099) {return false;}
    var daysInMonth=new Array(31,28,31,30,31,30,31,31,30,31,30,31);
        if (y%1000==0 ||(y%4==0 && y%100!=0)) {daysInMonth[1]=29;}
        if (d<1 || d>daysInMonth[m-1]) {return false;}
        return true;
  }


  function checkEmail(email)
  { // this checks for a valid format email address
    var pattern=/^[a-zA-Z0-9]+([.|_|-][a-zA-Z0-9]+)*[@]{1}[a-zA-Z0-9]+([.|_|-][a-zA-Z0-9]+)*[.]{1}[a-zA-Z0-9]{2,3}$/;
    var result=email.match(pattern);
    if (result==null)
      {
       return false;
      }
      else  return true;
  }


  function checkForm(f)
  {
//  alert ("Here in checkForm");
//  alert ("Name=" + f.name);

/*   To test the chosen option in a Select statement:
              var opt=f.selectname.selectedIndex;
                  var field=f.selectname.options[opt].text;

 (Can use value instead of text if the option statements have a value clause)
*/
    if (f.buttonPressed.value=="Cancel" || f.buttonPressed.value=="Back") {return true;}
    if (f.buttonPressed.value=="Delete")
    {
      if (confirm("Are you really sure you want to delete this record?"))
      {return true;}
      else {return false;}
    }
    var errMsg="";

    switch (f.name)
    {

      case "addressForm":
        if (empty(f.forename.value))
        {
          if (errMsg=="") {f.forename.focus();}
          errMsg+="Please enter your Forename\n";
        }

        if (empty(f.surname.value))
        {
          if (errMsg=="") {f.surname.focus();}
          errMsg+="Please enter your Surname\n";
        }
        if (empty(f.address1.value) && empty(f.address2.value) &&
            empty(f.address3.value) && empty(f.address4.value))
        {
          if (errMsg=="") {f.address1.focus();}
          errMsg+="Please enter your Address\n";
        }
        if (empty(f.postcode.value))
        {
          if (errMsg=="") {f.postcode.focus();}
          errMsg+="Please enter your Postcode\n";
        }

        if (empty(f.phone.value))
        {
          if (errMsg=="") {f.phone.focus();}
          errMsg+="Please enter your Telephone number\n";
        }
        else
        {
          var num=f.phone.value.replace(/ /g,"");

          if (num.length<11 || !isNumeric(num))
          {
            if (errMsg=="") {f.phone.focus();}
            errMsg+="Phone numbers must comprise at least 11 digits\n";
          }
        }

        if (empty(f.email.value))
        {
          if (errMsg=="") {f.email.focus();}
          errMsg+="Please enter your Email address\n";
        }
        else
        {
          if (!checkEmail(f.email.value))
          {
            if (errMsg=="") {f.email.focus();}
            errMsg+="That Email address is invalid\n";
          }
        }


        if ((!empty(f.nameAndAddressDelAddress1.value) || !empty(f.nameAndAddressDelAddress2.value) ||
             !empty(f.nameAndAddressDelAddress3.value) || !empty(f.nameAndAddressDelAddress1.value)) && empty(f.nameAndAddressDelPostcode.value))
        {          if (errMsg=="") {f.nameAndAddressDelPostcode.focus();}
          errMsg+="Please enter the Delivery Postcode\n";
        }
        if (empty(f.nameAndAddressDelAddress1.value) && empty(f.nameAndAddressDelAddress2.value) &&
            empty(f.nameAndAddressDelAddress3.value) && empty(f.nameAndAddressDelAddress1.value) && !empty(f.nameAndAddressDelPostcode.value))
        {
          if (errMsg=="") {f.nameAndAddressDelAddress1.focus();}
          errMsg+="Please enter the Delivery Address\n";
        }
      break;

      case "baseItemForm":
        if (empty(f.baseItemName.value))
        {
          if (errMsg=="") {f.baseItemName.focus();}
          errMsg+="Please enter the Item Name\n";
        }

        if (empty(f.baseItemDescription.value))
        {
          if (errMsg=="") {f.baseItemDescription.focus();}
          errMsg+="Please enter the Item Description\n";
        }

        if (empty(f.baseItemPrice.value))
        {
          if (errMsg=="") {f.baseItemPrice.focus();}
          errMsg+="Please enter the Item Price\n";
        }
        else
        {
          if (!isNumeric(f.baseItemPrice.value, 2))
          {
            if (errMsg=="") {f.baseItemPrice.focus();}
            errMsg+="The Item Price must be numeric with a maximum of 2 decimal places\n";
          }
        }

        if (empty(f.baseItemWeight.value))
        {
          if (errMsg=="") {f.baseItemWeight.focus();}
          errMsg+="Please enter the Item Weight\n";
        }
        else
        {
          if (!isNumeric(f.baseItemWeight.value))
          {
            if (errMsg=="") {f.baseItemWeight.focus();}
            errMsg+="The Item Weight must be numeric\n";
          }
        }
      break;

      case "categoryForm":
        if (empty (f.categoryName.value))
        {
           if (errMsg=="")  {f.categoryName.focus();}
           errMsg+="Please enter the Stocking Name\n";
        }

        if (empty (f.categoryItemPrice.value))
        {
           if (errMsg=="")  {f.categoryItemPrice.focus();}
           errMsg+="Please enter the Stocking Price\n";
        }
        else
        {
          if (!isNumeric(f.categoryItemPrice.value,2))
          {
            if (errMsg=="") {f.categoryItemPrice.focus();}
            errMsg+="The Stocking Price must be numeric, maximum 2 decimal places\n"
          }
        }

        /*
        if (empty (f.categoryWeight.value))
        {
           if (errMsg=="")  {f.categoryWeight.focus();}
           errMsg+="Please enter the Stocking Weight\n";
        }
        else
        {
          if (!isNumeric(f.categoryWeight.value))
          {
            if (errMsg=="") {f.categoryWeight.focus();}
            errMsg+="The Stocking Weight must be numeric\n"
          }
        }
        */
          if (!empty (f.categoryWeight.value) && !isNumeric(f.categoryWeight.value))
          {
            if (errMsg=="") {f.categoryWeight.focus();}
            errMsg+="The Stocking Weight must be numeric\n"
          }



        /*
        if (empty (f.categoryPostage.value))
        {
           if (errMsg=="")  {f.categoryPostage.focus();}
           errMsg+="Please enter the Postage\n";
        }
        else
        {
          if (!isNumeric(f.categoryPostage.value,2))
          {
            if (errMsg=="") {f.categoryPostage.focus();}
            errMsg+="The Postage must be numeric, maximum 2 decimal places\n"
          }
        }
        */
          if (!empty (f.categoryPostage.value) && !isNumeric(f.categoryPostage.value,2))
          {
            if (errMsg=="") {f.categoryPostage.focus();}
            errMsg+="The Postage must be numeric, maximum 2 decimal places\n"
          }



        /*
        if (empty (f.categoryPostageSpecial.value))
        {
           if (errMsg=="")  {f.categoryPostageSpecial.focus();}
           errMsg+="Please enter the Postage for Special Delivery\n";
        }
        else
        {
          if (!isNumeric(f.categoryPostageSpecial.value,2))
          {
            if (errMsg=="") {f.categoryPostageSpecial.focus();}
            errMsg+="The Postage for Special Delivery must be numeric, maximum 2 decimal places\n"
          }
        }
        */

          if (!empty (f.categoryPostageSpecial.value) && !isNumeric(f.categoryPostageSpecial.value,2))
          {
            if (errMsg=="") {f.categoryPostageSpecial.focus();}
            errMsg+="The Postage for Special Delivery must be numeric, maximum 2 decimal places\n"
          }




        if (Number(f.categoryPostage.value) > Number(f.categoryPostageSpecial.value))
        {
           if (errMsg=="")  {f.categoryPostage.focus();}
           errMsg+="The Special Delivery postage (" + f.categoryPostageSpecial.value + ") must not be less than the regular Postage" + f.categoryPostage.value + "\n";
        }

      break;

      case "contactForm":
        if (empty (f.contactName.value))
        {
           if (errMsg=="")  {f.contactName.focus();}
           errMsg+="Please enter your Name\n";
        }

/*
        if (empty (f.company.value))
        {
           if (errMsg=="")  {f.company.focus();}
           errMsg+="Please enter your Company Name\n";
        }
*/

        if (empty (f.address.value))
        {
           if (errMsg=="")  {f.address.focus();}
           errMsg+="Please enter your Address\n";
        }

        if (empty (f.postcode.value))
        {
           if (errMsg=="")  {f.postcode.focus();}
           errMsg+="Please enter your Postcode\n";
        }

        if (empty (f.phone.value))
        {
           if (errMsg=="")  {f.phone.focus();}
           errMsg+="Please enter your Telephone number\n";
        }
        else
        {
          if (!checkPhoneNo (f.phone.value))
          {
           if (errMsg=="")  {f.phone.focus();}
           errMsg+="Telephone numbers must be numeric, minimum 11 digits\n";
          }
        }

        if (empty (f.email.value))
        {
           if (errMsg=="")  {f.email.focus();}
           errMsg+="Please enter your Email address\n";
        }
        else
        {
          if (!checkEmail (f.email.value))
          {
           if (errMsg=="")  {f.email.focus();}
           errMsg+="That Email address is not valid\n";
          }
        }

        if (empty (f.comments.value))
        {
           if (errMsg=="")  {f.comments.focus();}
           errMsg+="Please enter details of your Enquiry\n";
        }
/*
        if (empty (f.spare1.value))
        {
           if (errMsg=="")  {f.spare1.focus();}
           errMsg+="Please enter your spare1\n";
        }

        if (empty (f.spare2.value))
        {
           if (errMsg=="")  {f.spare2.focus();}
           errMsg+="Please enter your spare2\n";
        }

        if (empty (f.spare3.value))
        {
           if (errMsg=="")  {f.spare3.focus();}
           errMsg+="Please enter your spare3\n";
        }

        if (empty (f.spare4.value))
        {
           if (errMsg=="")  {f.spare4.focus();}
           errMsg+="Please enter your spare4\n";
        }
*/
      break;

      case "ideacategoryForm":
        if (empty(f.ideacategoryName.value))
        {
          if (errMsg=="") {f.ideacategoryName.focus();}
          errMsg+="Please enter the Idea Category Name\n";
        }

        if (!empty(f.ideacategoryDisplaySequence.value) && !isNumeric(f.ideacategoryDisplaySequence.value))
        {
          if (errMsg=="") {f.ideacategoryDisplaySequence.focus();}
          errMsg+="If entered the Display Sequence must be numeric\n";
        }
      break;

      case "orderdetailForm":

        if (empty(f.orderdetailCategoryName.value))
        {
          if (errMsg=="") {f.orderdetailCategoryName.focus();}
          errMsg+="Please enter the Category Name\n";
        }

        if (empty(f.orderdetailQuantity.value))
        {
          if (errMsg=="") {f.orderdetailQuantity.focus();}
          errMsg+="Please enter the Quantity\n";
        }
        else
        {
          if (!isNumeric(f.orderdetailQuantity.value))
          {
            if (errMsg=="") {f.orderdetailQuantity.focus();}
            errMsg+="The Quantity must be numeric\n"
          }
        }
        /*
        if (empty(f.orderdetailField05.value))
        {
          if (errMsg=="") {f.orderdetailField05.focus();}
          errMsg+="Please enter the orderdetailField05\n";
        }

        if (empty(f.orderdetailField06.value))
        {
          if (errMsg=="") {f.orderdetailField06.focus();}
          errMsg+="Please enter the orderdetailField06\n";
        }
        */
      break;

      case "postageForm":
        if (empty(f.maximumWeight.value))
        {
          if (errMsg=="") {f.maximumWeight.focus();}
          errMsg+="Please enter the Maximum Weight\n";
        }
        else
        {
          if (!isNumeric(f.maximumWeight.value))
          {
            if (errMsg=="") {f.maximumWeight.focus();}
            errMsg+="The Maximum Weight must be numeric\n"
          }
        }

        if (empty(f.postage.value))
        {
          if (errMsg=="") {f.postage.focus();}
          errMsg+="Please enter the Postage\n";
        }
        else
        {
          if (!isNumeric(f.postage.value,2))
          {
            if (errMsg=="") {f.postage.focus();}
            errMsg+="The Postage must be numeric, maximum 2 decimal places\n"
          }
        }

        if (empty(f.specialDelivery.value))
        {
          if (errMsg=="") {f.specialDelivery.focus();}
          errMsg+="Please enter the Special Delivery Rate\n";
        }
        else
        {
          if (!isNumeric(f.specialDelivery.value,2))
          {
            if (errMsg=="") {f.specialDelivery.focus();}
            errMsg+="The Special Delivery Rate must be numeric, maximum 2 decimal places\n"
          }
        }
      break;

      default:
      return true;
    }

    if (errMsg!="")
    {
      alert(errMsg);
      return false;
    }
    else return true;
  }


  function checkPass(pass)
  { // This checks password is 6-12 chars, starts with a letter and contains
    // only alphanumerics

        if (pass.length<6 || pass.length>12) {return false;}
        var pattern=/^[a-zA-Z][a-zA-Z0-9]{0,11}$/;
    var result=pass.match(pattern);
    if (result==null)
      {
       return false;
      }
      else  return true;
  }

  function checkPhoneNo(phone)
  { // This checks a phone number contains at least 11 digits. It
    // ignores blanks and hyphens
        var p=phone.replace(/ |-/g,""); // Remove blanks or hyphens
        if (p.length<11 || !isNumeric(p)) {return false;}
        else {return true;}
  }

  function checkTime(h,m)
  {
    if (!isNumeric(h) || !isNumeric(m)) {return false;}
        if (h<0 || h>23) {return false;}
        if (m<0 || m>59) {return false;}
        return true;
  }

  function checkURL(URL)
  { // this checks for a valid format URL
    // NB this does not check anything beyond the basic address - ie no parameters
    var patternFormat=/^(http:\/\/)?[a-zA-Z0-9]+([.|_|-][a-zA-Z0-9]+)*[.]{1}[a-zA-Z0-9]{2,3}/;
    var result=URL.match(patternFormat);
    if (result==null)
      {
       return false;
      }
      else  return true;
  }

  function empty(s)
  {
    if (s=="" || s==null || isblank(s)) {return true;}
        else {return false;}
  }

  function generateRandomNo(x, y)
  { // This function generates a random integer between x & y
    var range = y - x + 1;
    return Math.floor(Math.random() * range) + x;
  }

  function getElement(id)
  {
    if (document.getElementById) {var elmt=document.getElementById(id);}
    else
    {
      if (document.all) {var elmt=document.all[id];}
          else
          {
            if (document.layers) {var elmt=document.layers[id];}
            else elmt=false;
          }
    }
    return elmt;
  }

  function isblank (s)
  { // Returns false if field contains any non-blank chars other than new line
    for (var i=0; i<s.length; i++) {
      var c=s.charAt(i);
          if (c!=" " && c!="\n" && c!="") {
          return false;
          }
    }
    return true;
  }


  function isNumeric (number, decPlaces)
  { // This function checks for numerics with a maximum of decPlaces decimal places
    var pattern="/^[0-9]+$/";
    if (decPlaces!='0')
    { // Decimal places allowed
      var dPlaces=2;
      var strPlaces=String(decPlaces);
      var result=strPlaces.match(pattern);
      if (result)  {dPlaces=decPlaces;}
      pattern=eval("/^[0-9]+([.][0-9]{1," + dPlaces + "})?$/");
    }
    var result=number.match(pattern);
    return result;
  }


  function makeTime(f, timeName)
  { // Returns a string containng the time in hh:mm form
    var opt=eval("f." + timeName + "Hour.selectedIndex");
        var hour=eval("f." + timeName + "Hour.options[opt].text");
        opt=eval("f." + timeName + "AmPm.selectedIndex");
        var amPm=eval("f." + timeName + "AmPm.options[opt].text");
        opt=eval("f." + timeName + "Minutes.selectedIndex");
        var minutes=eval("f." + timeName + "Minutes.options[opt].text");
        if (amPm=="pm" && hour!=12) {hour=Number(hour)+12;}
        else
        {
          if (hour<10) {hour="0"+hour;}
        }
        if (minutes<10) {minutes="0" + minutes;}
        return hour+":"+minutes;
  }



  function newWindow(url, w, h)
  { // Opens URL w in a new window positioned top left and ensures it has the focus
    if (!w) {var wide=400;} else {wide=w;}
        if (!h) {var high=450;} else {high=h;}
        var paras="width=" + wide + ",height=" + high + "align=center scrollbars=yes, left=0, top=0, screenx=0, screeny=0";
    var x=window.open(url, "newWindow", paras);
        x.window.focus();
  }

  function validateDate(f, dateName)
  {
        var opt=eval("f." + dateName + "Day.selectedIndex");
        var day=eval("f." + dateName + "Day.options[opt].text");
        opt=eval("f." + dateName + "Month.selectedIndex");
        var month=eval("f." + dateName + "Month.options[opt].value");
        opt=eval("f." + dateName + "Year.selectedIndex");
        var year=eval("f." + dateName + "Year.options[opt].text");
        return checkDate(day, month, year);
  }

  function validateSlashDate(ddmmyy)
  {
    var dateArray=ddmmyy.split("/");
        var d=dateArray[0];
        var m=dateArray[1];
        var y=dateArray[2];
        if (empty(d) || empty(m) || empty(y)) {return false;}
        var valid=checkDate(d, m, y);
        return valid;
  }