Policy on Intellectual Property Right (IPR)
Annex 1
Characteristics of teletext systems
1 Introduction
2 Definition of the teletext service
3 A layered model for describing teletext
systems
Layer 1: Physical
Layer 2: Link
Layer 3: Network
Layer 4: Transport
Layer 5: Session
Layer 6: Presentation
Layer 7: Application
4 Transmission characteristics
4.1 Data line (see Fig. 2)
4.2 Data unit (see Fig. 3)
4.3 Data packet (see Fig. 4)
4.4 Data group (see Fig. 5)
5 Presentation layer characteristics
5.1 Repertoires
5.1.1 Alphabets and
character sets
5.1.2 Special characters
5.2 Source coding
5.2.1 Alphanumeric coding
5.2.2 Mosaic coding
5.2.3 Dynamically
re-definable character sets (DRCS)
5.2.4 Geometric coding
5.2.5 Photographic coding
5.2.6 Musical sound data