// Start of generic validation functions
   
    // check for properly formed email   
    function emailCheck (thisfield) {
        var emailStr = thisfield.value;

        // email is optional (empty string is valid)
        if (emailStr == "") {
            return true;
		}        
       
        /* The following variable tells the rest of the function whether or not
        to verify that the address ends in a two-letter country or well-known
        TLD.  1 means check it, 0 means don't. */
        var checkTLD=1;

        /* The following is the list of known TLDs that an e-mail address must end with. */
        var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/;

        /* The following pattern is used to check if the entered e-mail address
        fits the user@domain format.  It also is used to separate the username
        from the domain. */
        var emailPat=/^(.+)@(.+)$/;

        /* The following string represents the pattern for matching all special
        characters.  We don't want to allow special characters in the address. 
        These characters include ( ) < > @ , ; : \ " . [ ] */
        var specialChars="\\(\\)><@,;:\\\\\\\"\\.\\[\\]";

        /* The following string represents the range of characters allowed in a 
        username or domainname.  It really states which chars aren't allowed.*/
        var validChars="\[^\\s" + specialChars + "\]";

        /* The following pattern applies if the "user" is a quoted string (in
        which case, there are no rules about which characters are allowed
        and which aren't; anything goes).  E.g. "jiminy cricket"@disney.com
        is a legal e-mail address. */
        var quotedUser="(\"[^\"]*\")";

        /* The following pattern applies for domains that are IP addresses,
        rather than symbolic names.  E.g. joe@[123.124.233.4] is a legal
        e-mail address. NOTE: The square brackets are required. */
        var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;

        /* The following string represents an atom (basically a series of non-special characters.) */
        var atom=validChars + '+';

        /* The following string represents one word in the typical username.
        For example, in john.doe@somewhere.com, john and doe are words.
        Basically, a word is either an atom or quoted string. */
        var word="(" + atom + "|" + quotedUser + ")";

        // The following pattern describes the structure of the user
        var userPat=new RegExp("^" + word + "(\\." + word + ")*$");

        /* The following pattern describes the structure of a normal symbolic
        domain, as opposed to ipDomainPat, shown above. */
        var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$");

        /* Finally, let's start trying to figure out if the supplied address is valid. */

        /* Begin with the coarse pattern to simply break up user@domain into
        different pieces that are easy to analyze. */

        var matchArray=emailStr.match(emailPat);

        if (matchArray==null) {           
            /* Too many/few @'s or something; basically, this address doesn't
            even fit the general mould of a valid e-mail address. */
            alert("Email address seems incorrect (check @ and .'s)");
			thisfield.focus();
			thisfield.select();
			return false;
        }       
    
        var user=matchArray[1];
        var domain=matchArray[2];       

        // Start by checking that only basic ASCII characters are in the strings (0-127).
        for (i=0; i<user.length; i++) {
            if (user.charCodeAt(i)>127) {
                alert("The username contains invalid characters.");
			    thisfield.focus();
			    thisfield.select();                
			    return false;
            }
        }
        for (i=0; i<domain.length; i++) {
            if (domain.charCodeAt(i)>127) {
                alert("The domain name contains invalid characters.");
			    thisfield.focus();
			    thisfield.select();                
			    return false;
            }
        }

        // See if "user" is valid 
        if (user.match(userPat)==null) {
            // user is not valid
            alert("The username doesn't seem to be valid.");
			thisfield.focus();
			thisfield.select();
			return false;
        }

        /* if the e-mail address is at an IP address (as opposed to a symbolic
        host name) make sure the IP address is valid. */

        var IPArray=domain.match(ipDomainPat);
        if (IPArray!=null) {
            // this is an IP address    
            for (var i=1;i<=4;i++) {
                if (IPArray[i]>255) {
                    alert("Destination IP address is invalid!");
			        thisfield.focus();
			        thisfield.select();
			        return false;
                }
            }
            return true;
        }

        // Domain is symbolic name.  Check if it's valid.
        var atomPat=new RegExp("^" + atom + "$");
        var domArr=domain.split(".");
        var len=domArr.length;
        for (i=0;i<len;i++) {
            if (domArr[i].search(atomPat)==-1) {
                alert("The domain name does not seem to be valid.");
			    thisfield.focus();
			    thisfield.select();                
			    return false;
            }
        }

        /* domain name seems valid, but now make sure that it ends in a
        known top-level domain (like com, edu, gov) or a two-letter word,
        representing country (uk, nl), and that there's a hostname preceding 
        the domain or country. */
        if (checkTLD && domArr[domArr.length-1].length!=2 && 
        domArr[domArr.length-1].toLowerCase().search(knownDomsPat)==-1) {
            alert("The email address must end in a well-known domain or two letter country.");
			thisfield.focus();
			thisfield.select();            
			return false;
        }

        // Make sure there's a host name preceding the domain.
        if (len<2) {
            alert("This email address is missing a hostname!");
			thisfield.focus();
			thisfield.select();
			return false;
        }

        // If we've gotten this far, everything's valid!
        return true;
    }    // function emailCheck ()   

	// thisfield - input value
	function check_numeric(thisfield) {
	    var valid = "0123456789";
		var ok = "yes";
		var singleChar = "";
		    
		// check for numeric values only
		for (var i=0; i<thisfield.value.length; i++) {
		    singleChar = thisfield.value.substring(i, i+1);
			// return the position where singleChar exists
			if (valid.indexOf(singleChar) == "-1") {
			    // singleChar not found within valid
			    ok = "no";
			}
		}
		if (ok == "no") {
		    alert("Please enter numbers only in this field");
			thisfield.focus();
			thisfield.select();
		}
	}    // function check_numeric()
	
	// thisfield - input value
	// flength - required input length, pass -1 if not required
	function check_numeric_length(thisfield,flength) {
	    var valid = "0123456789";
		var ok = "yes";
		var singleChar = "";
		    
		// check for numeric values only
		for (var i=0; i<thisfield.value.length; i++) {
		    singleChar = thisfield.value.substring(i, i+1);
			// return the position where singleChar exists
			if (valid.indexOf(singleChar) == "-1") {
			    // singleChar not found within valid
			    ok = "no";
			}
		}
		if (ok == "no") {
		    alert("Please enter numbers only in this field");
			thisfield.focus();
			thisfield.select();
		}
		// check if a length was specified
		else if (flength > -1) {
		    // check for proper length
		    if ((thisfield.value.length != 0) && (thisfield.value.length != flength)) {
		        alert("Please enter " + flength + " numbers in this field");
			    thisfield.focus();
			    thisfield.select();
		    }
		}
	}    // function check_numeric_length()

	// thisfield - input value
	// maxval - maximum value allowed
	function check_numeric_maxval(thisfield,maxval) {
	    var valid = "0123456789";
		var ok = "yes";
		var singleChar = "";
		var qty = 0;
		    
		if (thisfield.value != "") {
		    qty = parseInt(thisfield.value);
		}

		// check for numeric values only
		for (var i=0; i<thisfield.value.length; i++) {
		    singleChar = thisfield.value.substring(i, i+1);
			// return the position where singleChar exists
			if (valid.indexOf(singleChar) == "-1") {
			    // singleChar not found within valid
			    ok = "no";
			}
		}
		if (ok == "no") {
		    alert("Please enter numbers only in this field");
			thisfield.focus();
			thisfield.select();
		}
		    
		// check if greater than maxval
		else if (qty > maxval) {
            alert("The maximum quantity allowed is " + maxval);
            thisfield.focus();
            thisfield.select();
		}
	}    // function check_numeric_maxval()
		    
    // End of generic validation functions