Thanks for the input.  Here is what I ended up doing:



function checkit(theField)

{
if (Left(theField.value,1)=="~")
	{
	if (theField.value.length==14)
		 {

                 return true;
         }	
	else 
		{
		document.Search.SearchStr.value=theField.value;
		}
	}
else
	{
	
	var str = theField.value
	var pos = str.indexOf("~")
	document.Search.SearchStr.value=theField.value;
	if (pos>0)
	{
	
	document.Search.SearchStr.value="~";
	}

	}
}


in the <input>:

onKeyPress="if (checkit(this)) this.form.submit()"