MHEG - (Multimedia and Hypermedia Information Coding Experts Group) - MHEG includes an interactive middleware (software) used for digital terrestrial television. See IMPALA.

MHEG-5 - (Multimedia and Hypermedia information coding Experts Group) - The MHEG-5 standard was originally developed a decade ago and offers basic interactive facilities through a declarative description language. A working group is developing or has developed a specification to enable the use of a broadband return path with MHEG-5. Also see IMPALA.

www.mheg.org/users/mheg/faq.htm
New Zealand FreeView to use MHEG-5 for digital TV (informitv)

MHEG-3 - MHEG regarding scripting.

MHEG-6 - (Multimedia and Hypermedia information coding Expert Group) - MHEG standards and specifications were developed to increase MHEG-5's performance and access to various external services. MHEG-6 is often associated with advanced MHEG interactivity.