Bloomberg connection handle connection object bloomberg bloomberg close Bloomberg IDC yahoo connecting connection handle connection object Connection tab data default field header historical time series Data tab Datafeed dialog box default data dftool disconnecting fetch Bloomberg IDC yahoo field data field names Flag values get get Bloomberg IDC yahoot GETDATA argument graphical user interface HEADER argument header data header fields historical data HISTORY argument idc IP address isconnection Bloomberg IDC yahoo LOOKUP argument markets markets MATLAB root directory port number retrieve properties root directory MATLAB Securities Lookup dialog box Securities Lookup dialog box ticker symbols time series data TIMESERIES argument verification yahoo