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;
}
