current_next_indicator [MPEG-2 Semantics]
Some MPEG-2 private table sections permit the transmission of a "next" table section or sections to signal what a particular table will look like when it next changes. The MPEG-2 PSI tables that permit this are the PAT, CAT and PMT. ATSC tables that permit "next" editions include the TVCT, CVCT and SVCT. Most PSIP tables do not permit "next" editions.
The version_number in the next edition of the table must be the version_number of the current edition, incremented by 1 modulo 32, and that must be the actual version number transmitted upon the next table section change.
As a practical matter, next table sections are only useful when a table is comprised of more than one section. To minimize problems in receiver, "next" tables should NOT be sent well in advance of the change, and all "next" sections that comprise a table should be completely sent before the table actually changes.
When the version_number changes in the first section with the "current" indicator set, the receiver can substitute all the data in the "next" sections at the same moment, instead of waiting until all the changed sections are received.