function checkValidation ( addressField ) {
    if ( stringEmpty ( addressField.value ) )
        alert ( "Error! There is no E-Mail address entered" );
    else if ( noAtSign ( addressField.value ) )
        alert ( "Error! The E-Mail address does not contain an '@' character" );
    else if ( nothingBeforeAt ( addressField.value ) )
        alert ( "Error! An E-Mail address must contain at least one character before the '@' character" );
    else if ( noLeftBracket ( addressField.value ) )
        alert ( "Error! The E-Mail address contains a right square bracket ']',\nbut no corresponding left square bracket '['" );
    else if ( noRightBracket ( addressField.value ) )
        alert ( "Error! The E-Mail address contains a left square bracket '[',\nbut no corresponding right square bracket ']'" );
    else if ( noValidPeriod ( addressField.value ) )
        alert ( "Error! An E-Mail address must contain a period ('.') character" );
    else if ( noValidSuffix ( addressField.value ) )
        alert ( "Error! An E-Mail address must contain a two or three character suffix" );
    else
        return (true);

    return ( false );
}

function linkCheckValidation ( formField ) {
    if ( checkValidation ( formField ) == true ) {
        alert ( 'E-Mail Address Validates OK' );
    }

    return ( false );
}

function stringEmpty ( address ) {
    // CHECK THAT THE STRING IS NOT EMPTY
    if ( address.length < 1 ) {
        return ( true );
    } else {
        return ( false );
    }
}

function noAtSign ( address ) {
    // CHECK THAT THERE IS AN '@' CHARACTER IN THE STRING
    if ( address.indexOf ( '@', 0 ) == -1 ) {
        return ( true )
    } else {
        return ( false );
    }
}

function nothingBeforeAt ( address ) {
    // CHECK THERE IS AT LEAST ONE CHARACTER BEFORE THE '@' CHARACTER
    if ( address.indexOf ( '@', 0 ) < 1 ) {
        return ( true )
    } else {
        return ( false );
    }
}

function noLeftBracket ( address ) {
    // IF EMAIL ADDRESS IN FORM 'user@[255,255,255,0]', THEN CHECK FOR LEFT BRACKET
    if ( address.indexOf ( '[', 0 ) == -1 && address.charAt ( address.length - 1 ) == ']' ) {
        return ( true )
    } else {
        return ( false );
    }
}

function noRightBracket ( address ) {
    // IF EMAIL ADDRESS IN FORM 'user@[255,255,255,0]', THEN CHECK FOR RIGHT BRACKET
    if ( address.indexOf ( '[', 0 ) > -1 && address.charAt ( address.length - 1 ) != ']' ) {
        return ( true );
    } else {
        return ( false );
    }
}

function noValidPeriod ( address ) {
    // IF EMAIL ADDRESS IN FORM 'user@[255,255,255,0]', THEN WE ARE NOT INTERESTED
    if ( address.indexOf ( '@', 0 ) > 1 && address.charAt ( address.length - 1 ) == ']' )
        return ( false );

    // CHECK THAT THERE IS AT LEAST ONE PERIOD IN THE STRING
    if ( address.indexOf ( '.', 0 ) == -1 )
        return ( true );

    return ( false );
}

function noValidSuffix ( address ) {
    // IF EMAIL ADDRESS IN FORM 'user@[255,255,255,0]', THEN WE ARE NOT INTERESTED
    if ( address.indexOf ( '@', 0 ) > 1 && address.charAt ( address.length - 1 ) == ']' )
        return ( false );

    // CHECK THAT THERE IS A TWO OR THREE CHARACTER SUFFIX AFTER THE LAST PERIOD
    var len = address.length;
    var pos = address.lastIndexOf ( '.', len - 1 ) + 1;
    if ( ( len - pos ) < 2 || ( len - pos ) > 3 ) {
        return ( true );
    } else {
        return ( false );
    }
}














<!-- HIDE FROM OLD BROWSERS

function numbersonly(myfield, e, dec)
{
var key;
var keychar;

if (window.event)
   key = window.event.keyCode;
else if (e)
   key = e.which;
else
   return true;
keychar = String.fromCharCode(key);

// control keys
if ((key==null) || (key==0) || (key==8) || 
    (key==9) || (key==13) || (key==27) )
   return true;

// numbers
else if ((("0123456789").indexOf(keychar) > -1))
   return true;

// decimal point jump
else if (dec && (keychar == "."))
   {
   myfield.form.elements[dec].focus();
   return false;
   }
else
   return false;
}

// END HIDING -->



function Show_Stuff(Click_Menu)
// Function that will swap the display/no display for
// all content within span tags
{
if (Click_Menu.style.display == "none")
{
Click_Menu.style.display = "";
}
else
{
Click_Menu.style.display = "none";
}
}


<!--

  function Require(obForm,szFields)
    {
      var fields = szFields.split(",")
      var szMissing= new Array();
      for (x=0;x<fields.length;x++) {
        if (obForm.elements[fields[x]].value.length==0) {
           szMissing[szMissing.length]=new String(fields[x]);
        }
      }
      if (szMissing.length) {
        alert("Incomplete form! Following fields missing:                                     "+((szMissing.length>1)?"":" ")+szMissing.join(" * ")+"");
        return false
      }
      return true;
    }
//-->




function autotab(original,destination){
if (original.getAttribute&&original.value.length==original.getAttribute("maxlength"))
destination.focus()
}


   
      <!--
      function isNumberKey(evt)
      {
         var charCode = (evt.which) ? evt.which : event.keyCode
         if (charCode > 31 && (charCode < 48 || charCode > 57))
            return false;

         return true;
      }
      //-->