Most radio and modem clocks used for a primary (stratum-1) NTP server utilize serial ports operating at speeds of 9600 baud or greater. ... In order to reduce these errors, a set of special line disciplines and stream modules can be configured in the Unix kernel. ... Note that not all Unix kernels support line disciplines and of those that do, not all support System V streams. ... There are two line disciplines and a special streams module included in the distribution. ...