"The present document provides implementation guidelines for the use and implementation of the DVB Service Information (SI) coding in a DVB digital TV environment including satellite- cable- and terrestrial networks. The guidelines are intended to be highly recommended rules for the usage of the DVB SI syntax specified in EN 300 468 [i.1]. As such@ they facilitate the efficient and reliable implementation of basic user-interaction functions in Integrated Receiver-Decoders (IRD). The rules apply to broadcasters@ network operators as well as manufacturers. The rules are specified in the form of constraints on the DVB SI streams or in terms of intended interpretation by IRDs. The specification of these functions in no way prohibits IRD manufacturers from including additional features@ and should not be interpreted as stipulating any form of upper limit to the performance. The guidelines do not cover features related to user-interface details or advanced Electronic Program Guides (EPG). Such issues are left to the marketplace. NOTE: It is highly recommended that the IRD should be designed to allow for future compatible extensions to the DVB SI syntax. All the fields ""reserved"" (for ISO)@ ""reserved_future_use"" (for ETSI)@ and ""user defined"" in the EN 300 468 [i.1] should be ignored by IRDs designed not to make use of them. The ""reserved"" and ""reserved_future_use"" fields may be specified in the future by the respective bodies@ whereas the ""user defined"" fields will not be standardized. The present document uses the terminology defined in EN 300 468 [i.1] and should be read in conjunction with that EN."