Hi Apsattv,<br /><br />Check out ETSI TR 101 211 v1.4.1(2000-07) - there maybe latter versions?<br /><br />"DVB Guidelines on Implementation and usage of Service Infermation."<br /><br />One relevent paragraph is: <br /><br />"4.1.10 Table update mechanism<br />The section syntax used in the DVB Service Information (SI) supports various signalling mechanisms for SI contents<br />updates.<br />The update of a section will be signalled by incrementing the version_number field. The update will be effective<br />immediately following the last byte of the CRC_32 of the new version of the section, so the current_next_indicator shall<br />always have the value of "1". Sections with current_next_indicator set to "0" are never transmitted."<br /><br />The usual STB implementation is for the box to remenber and monitor the version_number of the SI tables that it has in memory, when it sees the version_number increments, it re-aquires the SI - this way the STB doesn'tneed to spend excessive MIPS processing SI. This mechanism is common to most (if not all) DVB tables. Both DVB and MPEG are designed to by asymetric coding schemes, they trade off increased complexity (MIPS and cost) in the headend for lower complexity 9MIPS & cost^) in the STB.