one Mexican station was able to change its virtual channel. Australia In Australia, allocation of logical channel numbers is governed by guidelines set by the commercial broadcasters' association, Free TV Australia. These are defined within the terrestrial broadcast stream using the NorDig descriptor format within the DVB "Network Information Table." LCNs in Australia may have one, two or three digits. Each network is allocated LCNs starting with a certain prefix - for instance, all metropolitan Nine Network services use LCNs beginning with the digit '9'. Generally, but not always, the single-digit LCN is allocated to the primary SD service (Network 10's high definition-channel 10 HD being the main exception). LCNs need not be contiguous, and a channel may be identified by more than one LCN. For instance, ABC Television's primary ABC TV service is allocated LCNs 2 and 21; the latter allows it to be easily accessed amongst other ABC services which lie in the 21–24 range. Regional affiliates of the three metropolitan networks are provided with a different LCN prefix. For instance, channels owned by affiliates of the Nine Network (in this case NBN Television) are prefixed with the digit '8' rather than '9'. This allows areas that are part of both a metropolitan market and a regional market, such as the Gold Coast, Sunshine Coast and Central Coast, to receive all local commercial services. The ABC and SBS use the same prefix in all areas. Prefixes for remote-area services are intended to be overlaid over this model. When digital transmission starts in these areas, services licensed for the Remote Central and Eastern Australia licence area (Imparja and Southern Cross Central) have been reserved the "metropolitan" prefixes corresponding to their affiliation; those in Remote Western Australia (GWN and WIN WA) the "regional" prefixes. A number of LCNs are reserved for various reasons: LCN 4 was originally intended for a free-to-air video program guide. In practice, the LCN 4 prefix has for most of its life been largely unused, except in Sydney (where it was used by the Digital Forty Four trial datacasting service from 2004 to 2010). Since 2010, capital city community television stations (or "Channel 31" stations, after their typical analogue channel position) use LCN 44. The LCN range 350-399 is intended to be allocated by receivers to channels which either duplicate a stronger signal's LCN, or are transmitted without an LCN. For instance, if two broadcasts of