function get_po( event )
{
	//----------------------------------
	// INIT
	//----------------------------------
	
	Check = 1;
	var error_found = '';
		
	//----------------------------------
	// Ajax: check for existing email address
	//----------------------------------
	var url = var_base_url + "/common/xmlout.php";
	var query = "xmlhttp=yes&method=pocheck&po=" + escape(document.getElementById('po').value);
	
	do_request_function = function()
	{			
		if ( ! xmlobj.readystate_ready_and_ok() )
		{
			return;
		}
		
		//----------------------------------
		// INIT
		//----------------------------------
		
		response = xmlobj.xmlhandler.responseText.parseJSON();
		
		//----------------------------------
		// Show errors
		//----------------------------------
		
		if ( response.success )
		{
			document.getElementById('po').className = "input-green";
			document.getElementById('po-num-msg').innerHTML = response.ErrorMsg;
		}
		else
		{
			document.getElementById('po').className = "input-red";
			document.getElementById('po-num-msg').innerHTML = response.ErrorMsg;
		}
		
		error_found = '';
	}
	
	//----------------------------------
	// LOAD XML
	//----------------------------------
	
	xmlobj = new ajax_request();
	xmlobj.onreadystatechange( do_request_function );
	xmlobj.process( url , "POST" , query );
}