The DVB Standard is "sitting on top" of the MPEG2 standard. It contains specifications for various additional System Information tables that simplify the channel acquisition and that are the basis for a useful EPG.

The DVB Standard is published by the ETSI and can be downloaded free of charge if you provide a valid email-adress and complete the (quite useless) registration. 

The DVB core document has the number ETSI EN 300 468 and has the title:

Specification for Service Information (SI) in DVB systems

Several other digital tv standards have been published by the ETSI. Some of them are followups to the document mentioned above. They just contain new numbers, descriptors or clarifications. Other documents like the Common Interface Specification are (no longer) available for public download.

You can find more about the various DVB standards at http://www.dvb.org