function isNumericKeyStroke()
{
    var returnValue = false;
    var keyCode = (window.event.which) ? window.event.which : window.event.keyCode;

    if (((keyCode >= 48) && (keyCode <= 57)) || // All numerics
                       (keyCode == 8) ||     // Backspace
                       (keyCode == 13) || (keyCode == 96) ||
                       (keyCode == 97) ||
                       (keyCode == 98) ||
                       (keyCode == 99) ||
                       (keyCode == 100) ||
                       (keyCode == 101) ||
                       (keyCode == 102) ||
                       (keyCode == 103) ||
                       (keyCode == 104) ||
                       (keyCode == 105) ||
                       (keyCode == 189))     // Carriage Return
        returnValue = true;

    if (window.event.returnValue)
        window.event.returnValue = returnValue;

    return returnValue;
}