Conditional Access	Software/hardware used to limit unauthorised access to broadcast programmes. Typically used for pay tv services. A choice between some half dozen proprietary products is available.
DDN	Digital Data Network - a digital transmission using satellite formats, but transmitted from terrestrial sites, proposed for operation in the 12 GHz bands.
DTT	Digital Terrestrial Television - digital services transmitted from a network of sites, typically using frequencies in the UHF bands.
DVB	Digital Video Broadcasting - a family of digital transmission standards covering satellite, cable and terrestrial broadcasting.
MHP	Multimedia Home Platform - a non proprietary facility being developed that allows interactive applications within the DVB family of standards.
Open TV	A developed proprietary facility that allows interactive applications on digital services. Used by Sky in New Zealand.
Set Top Box	Receiver/decoder used to convert digital signals to present television formats. Can provide conditional access control and advanced features such as interactive applications.>
UHF	Ultra High Frequency - a band of frequencies from 500-800 MHz used for television broadcasting, including Sky terrestrial, Prime, TAB and regional non-commercial broadcasts.
VHF	Very High Frequency - a band of frequencies from 50-230 MHz used for television broadcasting, including TV One, TV2, TV3, and TV4.
12 GHz	Frequencies used for satellite broadcasting and other terrestrial uses.

Crown Copyright 2001. All Rights Reserved: No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the copyright holders, the Ministry of Economic Development, New Zealand.