SIST ETS 300 382 E1:2003
(Main)Terminal Equipment (TE); Videotex Enhanced Man Machine Interface service (VEMMI)
Terminal Equipment (TE); Videotex Enhanced Man Machine Interface service (VEMMI)
Definition of objects (menu buttons, checking boxes,...) necessary to provide videotex with an enhanced man machine interface. Specification of the associated protocol elements in the syntax-based vidotex (SBV) protocol.
Terminalska oprema (TE) – Izboljšana storitev vmesnika človek-stroj pri sistemu Videotex (VEMMI)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2003
7HUPLQDOVNDRSUHPD 7( ±,]EROMãDQDVWRULWHYYPHVQLNDþORYHNVWURMSULVLVWHPX
9LGHRWH[ 9(00,
Terminal Equipment (TE); Videotex Enhanced Man Machine Interface service (VEMMI)
Ta slovenski standard je istoveten z: ETS 300 382 Edition 1
ICS:
33.160.99 Druga avdio, video in Other audio, video and
avdiovizuelna oprema audiovisual equipment
35.180 Terminalska in druga IT Terminal and other
periferna oprema IT peripheral equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN ETS 300 382
TELECOMMUNICATION February 1995
STANDARD
Source: ETSI TC-TE Reference: DE/TE-01016
ICS: 33.020, 33.040.40
Videotex, Man Machine Interface, VEMMI
Key words:
Terminal Equipment (TE);
Videotex Enhanced Man Machine Interface service (VEMMI)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - secretariat@etsi.fr
X.400: Internet:
Tel.: +33 92 94 42 00 - Fax: +33 93 65 47 16
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1995. All rights reserved.
New presentation - see History box
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ETS 300 382: February 1995
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.
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ETS 300 382: February 1995
Contents
Foreword .9
1 Scope .11
2 Normative references.11
3 Definitions and abbreviations .12
3.1 Definitions .12
3.2 Abbreviations .13
4 General model.14
4.1 Introduction .14
4.2 Definition of the VEMMI elements .14
4.2.1 VEMMI object definition.14
4.2.2 VEMMI component definition .15
4.2.3 VEMMI component item definition.15
4.3 VEMMI logical plane structure model .15
4.3.1 The standard Videotex logical plane .16
4.3.2 The VEMMI objects logical plane.16
4.4 Operation modes for VEMMI terminals.16
4.4.1 The standard Videotex mode .16
4.4.2 The VEMMI mode .16
4.4.3 Switching between standard Videotex mode and VEMMI mode.17
4.5 VEMMI elements data content.17
4.5.1 Text data definition.17
4.5.2 Videotex data definition .18
4.6 VEMMI objects positioning and dimensioning .18
4.6.1 Positioning.18
4.6.2 Dimensioning.19
4.7 VEMMI elements states and state parameters.21
4.7.1 Object.21
4.7.1.1 Definition of object states .22
4.7.1.2 Definition of object state parameters.23
4.7.2 Component.24
4.7.2.1 Definition of component states .24
4.7.2.2 Definition of component state parameters.25
4.8 Local action management.25
4.9 Storage considerations .26
4.10 Common rules for object handling.27
4.10.1 Active state and focus management.27
4.10.2 Behaviour of the modal mode .27
4.10.3 Size considerations and clipping .27
5 Service definition .28
5.1 Service elements initiated by the VEMMI application .29
5.1.1 VEMMI_On.29
5.1.2 VEMMI_Off.30
5.1.3 VEMMI_Create_Object .30
5.1.4 VEMMI_Open_Object .30
5.1.5 VEMMI_Close_Object.31
5.1.6 VEMMI_Close_All.31
5.1.7 VEMMI_Destroy_Object.31
5.1.8 VEMMI_Obj_Access_Disable .32
5.1.9 VEMMI_Obj_Access_Enable .32
5.1.10 VEMMI_Additional_Data .32
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ETS 300 382: February 1995
5.1.11 VEMMI_Modify_Component. 33
5.1.12 VEMMI_Obj_Location_Change . 33
5.1.13 VEMMI_User_Lock. 33
5.1.14 VEMMI_User_Unlock . 34
5.1.15 VEMMI_Reset. 34
5.2 Service elements initiated by the terminal. 34
5.2.1 VEMMI_Object_Retransmission. 34
5.2.2 VEMMI_More_Data . 35
5.2.3 VEMMI_User_Data. 35
5.2.4 VEMMI_Error . 36
6 VEMMI objects introduction. 37
6.1 The Application Bar. 37
6.1.1 Composition. 37
6.2 The Button Bar . 37
6.2.1 Composition. 37
6.3 The Pop-Up Menu. 38
6.3.1 Composition. 38
6.4 The Dialogue Box. 38
6.4.1 Composition. 38
6.4.1.1 The Separator component . 38
6.4.1.2 The Frame component . 39
6.4.1.3 The Text Presentation Area component . 39
6.4.1.4 The Videotex Presentation Area component . 39
6.4.1.5 The Push Button component . 39
6.4.1.6 The Text Input Field component . 39
6.4.1.7 The Check Box component . 39
6.4.1.8 The Radio Button component . 39
6.4.1.9 The List Box component . 39
6.4.1.10 The Combination Box component. 39
6.4.1.11 The Sensitive Area component. 40
6.4.1.12 The Locator component. 40
6.5 The Presentation Box. 40
6.5.1 Composition. 40
6.5.1.1 The Text-Videotex Output Field component . 40
6.5.1.2 The Push Button component . 40
6.5.1.3 The Text Input Area . 40
6.5.1.4 The Sensitive Area component. 40
6.5.1.5 The Locator component. 41
6.6 The Message Box . 41
7 Functional description. 41
7.1 General rules for the behaviour of elements. 41
7.1.1 User Interaction . 41
7.1.2 Local actions and reports. 41
7.1.3 Relationship between objects and components . 42
7.1.4 VEMMI elements with audio data content . 42
7.2 The Application Bar. 42
7.2.1 Composition. 46
7.2.1.1 Menu Choice Bar components. 46
7.2.1.2 Menu Choice Pull-Down components. 48
7.2.1.3 Menu Choice Cascading components . 50
7.2.1.4 Menu Choice Separator components . 51
7.3 The Button Bar . 52
7.3.1 Composition. 54
7.3.1.1 The Button component. 54
7.4 The Pop-Up Menu. 55
7.4.1 Composition. 57
7.4.1.1 Menu Choice Pop-Up components. 57
7.4.1.2 Menu Choice Cascading components . 59
7.4.1.3 Menu Choice Separator components . 59
7.5 The Dialogue Box. 60
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ETS 300 382: February 1995
7.5.1 Composition .62
7.5.1.1 The Separator component.62
7.5.1.2 The Frame component .64
7.5.1.3 The Text Presentation Area component.65
7.5.1.4 The Videotex Presentation Area component.66
7.5.1.5 The Push Button component.67
7.5.1.6 The Text Input Field component.68
7.5.1.7 The Check Box component .70
7.5.1.8 The Radio Button component.71
7.5.1.9 The List Box component.73
7.5.1.10 The Combination Box component .75
7.5.1.11 The Sensitive Area component .78
7.5.1.12 The Locator component.80
7.6 The Presentation Box .81
7.6.1 Composition .84
7.6.1.1 The Text-Videotex Output Field component.84
7.6.1.2 The Push Button component.88
7.6.1.3 The Text Input Area component.88
7.6.1.4 The Sensitive Area component .90
7.6.1.5 The Locator component.91
7.7 The Message Box.91
8 Coding of the service elements.94
8.1 Overall switching of coding environment .94
8.2 Switching into the VEMMI mode.96
8.3 ISO/IEC 9281 syntax structure .96
8.4 Coding of the Picture Data Entity (PDE) .97
8.5 Object specific commands.98
8.6 General commands .98
8.7 Terminal commands .99
8.8 Error Message .99
8.9 Coding of the VEMMI command fields .100
8.9.1 Command Code .100
8.9.2 Object Identification Number (OIN).101
8.9.3 More Data Indicator (MDI).101
8.9.4 User data.101
9 Coding of the VEMMI data .102
9.1 Structure of the VEMMI data of a VEMMI_Create_Object command .102
9.2 Structure of the VEMMI data of a VEMMI_Modify_Component command .103
9.3 Structure of the VEMMI data of a VEMMI_Additional_Data command .104
9.4 Structure of the VEMMI data of a VEMMI_Obj_Location_Change command.105
9.5 Structure of the VEMMI data of a VEMMI_More_Data command.105
9.6 Structure of the VEMMI data of a VEMMI_User_Data command .106
9.6.1 Coding of the report values for VEMMI components .106
9.6.1.1 Menu Choice Bar, Menu Choice Pull-Down, Menu Choice
Cascading, Menu Choice Pop-Up, Push Button, Button
Sensitive Area.106
9.6.1.2 Text Input Field, List Box, Combination Box.107
9.6.1.3 Check Box, Radio Button .107
9.6.1.3.1 Locator.107
9.7 Structure of the VEMMI data of a VEMMI_Error command.108
9.7.1 Coding of the error message.108
9.8 General rules for coding VEMMI data.109
9.9 Code assignments for VEMMI objects and components.113
9.10 Coding of VEMMI elements .113
9.10.1 Application Bar .113
9.10.1.1 Menu Choice Bar, Menu Choice Pull-Down, Menu Choice
Cascading, Menu Choice Pop-Up components.114
9.10.1.2 Menu Choice Separator component.115
9.10.2 Button Bar .115
9.10.2.1 Button .116
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ETS 300 382: February 1995
9.10.3 Pop-Up Menu. 117
9.10.3.1 Menu Choice Pop-Up, Menu Choice Cascading
components . 118
9.10.4 Dialogue Box . 118
9.10.4.1 Separator . 119
9.10.4.2 Frame. 120
9.10.4.3 Text Presentation Area . 121
9.10.4.4 Videotex Presentation Area . 122
9.10.4.5 Push Button. 123
9.10.4.6 Text Input Field . 124
9.10.4.7 Check Box. 126
9.10.4.8 Radio Button . 127
9.10.4.9 List Box . 128
9.10.4.10 Combination Box. 129
9.10.4.11 Sensitive Area. 131
9.10.4.12 Locator . 132
9.10.5 Presentation Box . 133
9.10.5.1 Text-Videotex Output Field . 135
9.10.5.2 Push Button. 135
9.10.5.3 Text Input Area . 136
9.10.5.4 Sensitive Area. 137
9.10.5.5 Locator . 138
9.10.6 Message Box. 139
9.10.7 Coding of local actions. 141
9.11 Attribute field type codes . 143
10 Introduction of the VEMMI service into existing Videotex ETSs. 144
10.1 Introduction of the VEMMI to ETS 300 072. 144
10.2 Introduction of the VEMMI to ETS 300 223 and ETS 300 079. 144
Annex A (normative): T.51String . 145
A.1 Introduction. 145
A.2 Graphic character sets . 145
A.3 Code extension technique . 147
A.4 Repertoire of the latin based character set. 147
A.5 Control functions. 147
Annex B (informative): Future VEMMI concepts . 147
B.1 Local object storage. 147
B.1.1 VEMMI_OpenApplication . 148
B.1.2 VEMMI_OpenApplicationResponse. 148
B.1.3 VEMMI_StoreObjects. 148
B.1.4 VEMMI_StoreObjectsResponse . 149
B.2 Operative objects. 149
B.2.1 VEMMI_ExecuteProgram. 149
B.3 Colour table . 149
B.3.1 VEMMI_LoadColTable . 150
B.3.2 VEMMI_ResetColTable. 150
B.4 Set of Objects concept . 150
B.4.1 VEMMI_CreateSetofObjects . 151
B.5 Coding . 151
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B.6 Provisional command codes .151
History.152
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ETS 300 382: February 1995
Foreword
This European Telecommunication Standard (ETS) was produced by the Terminal Equipment (TE)
Technical Committee of the European Telecommunications Standards Institute (ETSI).
Annex A is normative to this ETS while annex B is informative.
Proposed transposition dates
Date of latest announcement of this ETS (doa): 31 May 1995
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 30 November 1995
Date of withdrawal of any conflicting National Standard (dow): 30 November 1995
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ETS 300 382: February 1995
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ETS 300 382: February 1995
1 Scope
This ETS specifies the data syntax to be used by Videotex services for implementation of the Videotex
Enhanced Man Machine Interface (VEMMI).
This ETS is applicable to both the Videotex service and the attached Videotex terminals. Those terminals
may be connected to the Videotex service via the Public Switched Telephone Network (PSTN), Integrated
Services Digital Network (ISDN) or Packet Switched Public Data Network (PSPDN).
Typically, the terminals should support ISDN Syntax-Based Videotex (SBV).
This ETS also applies to any equipment (e.g. another Videotex service) which acts as a Videotex terminal.
2 Normative references
This ETS incorporates by dated and undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references the last
edition of the publication referred to applies.
[1] ETS 300 072: "Terminal Equipment (TE); Videotex presentation layer protocol,
Videotex presentation layer data syntax".
[2] ETS 300 073: "Videotex presentation layer protocol; Geometric Display (CEPT
Recommendation T/TE 06-02, Edinburgh 1988)".
[3] ETS 300 076 (1992): "Terminal Equipment (TE); Videotex, Terminal Facility
Identifier (TFI)".
[4] ETS 300 079: "Integrated Services Digital Network (ISDN); Syntax-based
Videotex, End-to-end protocols, circuit mode DTE-DTE".
[5] ETS 300 149: "Terminal Equipment (TE); Videotex, Audio syntax".
[6] ETS 300 177: "Terminal Equipment (TE); Videotex, Photographic syntax".
[7] ETS 300 223: "Terminal Equipment (TE); Syntax-based Videotex, Common
end-to-end protocols".
[8] ITU-T Recommendation T.50: "International Reference Alphabet (IRA)
(Formerly International Alphabet No.5 or IA5) - Information technology - 7 bit
coded character set for information interchange".
[9] ITU-T Recommendation T.51: "Latin based coded character sets for telematic
services".
[10] ITU-T Recommendation T.101 (1993): "International interworking for videotex
services".
[11] ITU-T Recommendation F.300: "Videotex service".
[12] ISO/IEC 9281 (1990): "Information technology - Picture coding methods".
[13] ITU-T Recommendation T.52: "Non-latin coded character sets for telematic
services".
[14] ISO 2022 (1986): "Information Processing - ISO 7-bit and 8-bit coded character
sets - Code extension techniques".
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ETS 300 382: February 1995
[15] ISO 2375 (1991): "Data Processing - Procedure for registration of escape
sequences".
[16] ISO 10918-1: "Digital compression and coding of continuous-tone still images -
Part 1: Requirements and guidelines".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of this ETS, the following definitions apply:
anticipation: Optional facility for a VEMMI application to send closed objects or objects with closed
components to a VEMMI terminal which supports this option.
controls: Visual user-interface elements that allows a user to interact with data.
Defined Display Area (DDA): The rectangular part of the screen that can be used by the Videotex service
[ITU-T Recommendation F.300 [11]].
emphasis: Highlighting, colour change, or other visible indication of the condition of an element or choice
and the effect of that condition on a user's ability to interact with that element. Emphasis can also give
additional information about the state of an object. The method used to emphasise an element is terminal
dependent.
label: Text data associated with a VEMMI component, to inform the user of the purpose of a particular
component or item.
local manager: See VEMMI local manager.
mnemonic: A single, easy-to-remember alphanumeric character that activates a VEMMI Menu Choice
component and validates it. A Mnemonic character can also be used to validate an active Push Button in a
Dialogue Box and a Button in an active Button Bar.
modal mode: When a VEMMI object is "modal", the user cannot leave this VEMMI object to the benefit of
another VEMMI object of the same application with the different possible access tools. Each attempt to
access another object by the user is refused and possibly indicated by a sound signal.
standard Videotex application: Videotex application using encoded data, protocols and profiles, as
defined in the Videotex ETSs referenced in clause 2. A standard Videotex application does not use a
VEMMI service, data and protocols.
standard Videotex data: Data interchanged between a standard Videotex application and a Videotex
terminal.
validation: User activation action followed by a confirmation of the choice with a keyboard or with a
pointing device.
VEMMI application: Videotex application offering an enhanced man machine interface as described in
this ETS.
VEMMI data: VEMMI objects description and contents and VEMMI commands exchanged between the
VEMMI application and the VEMMI terminal.
VEMMI local manager: Software running in the VEMMI terminal to handle and to present the VEMMI
objects that are sent to the user by the VEMMI application.
VEMMI terminal: Videotex terminal which is able to run a VEMMI local manager.
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ETS 300 382: February 1995
Videotex application: Part of a Videotex service which is under the responsibility of only one application
provider. The Videotex service provider may also act as an application provider [ITU-T Recommendation
F.300 [11]].
Videotex Host Computer: The computer (or network of computers provided by a single party) on which
one or more applications are implemented and/or one or more other Videotex service facilities are
provided [ITU-T Recommendation F.300 [11]].
Videotex terminal: The equipment by means of which the user interacts with the Videotex service. A
typical Videotex terminal includes:
1) a numeric keypad and/or alphanumeric keyboard and/or other graphical input devices;
2) a visual display unit or a suitably modified television receiver;
3) electronic processing and storage devices required to interface these components to the
telecommunications network and to generate the display.
3.2 Abbreviations
For the purposes of this ETS, the following abbreviations apply:
CIN Component Identification Number
CMI Coding Method Identifier
CR Carriage Return
DDA Defined Display Area
DRCS Dynamically Redefinable Character Set
DS I Data Syntax according to ITU-T Recommendation T.101 [10], annex B
DS II Data Syntax according to ITU-T Recommendation T.101 [10], annex C
DS III Data Syntax according to ITU-T Recommendation T.101 [10], annex D
ESC Escape
IRV International Reference Version
ISDN Integrated Services Digital Network
LF Line Feed
LI Length indicator
MDI More Data Indicator
NDC Normalised Device Co-ordinate
OIN Object Identification Number
PCD Picture Coding Delimiter
PCE Picture Control Entity
PDE Picture Data Entity
PE Picture Entity
PI Picture Identifier
PM Picture Mode
PSPDN Packet Switched Public Data Network
PSTN Public Switched Telephone Network
SBV Syntax-Based Videotex
TE Terminal Equipment
TFI Terminal Facility Identifier
VPDE Videotex Presentation Data Element
VEMMI Videotex Enhanced Man Machine Interface
VTX Videotex
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ETS 300 382: February 1995
4 General model
4.1 Introduction
Between a host and a VEMMI terminal, a VEMMI service handles:
- general VEMMI objects as described in this ETS;
- text and Videotex encoded data contents as described in the Videotex ETSs referenced in
clause 2.
A VEMMI terminal shall also handle a standard Videotex application using encoded data and protocols as
described in the Videotex ETSs referenced in clause 2.
4.2 Definition of the VEMMI elements
The logical units which form the structure of the VEMMI shall be named and defined as follows:
- VEMMI objects or objects;
- VEMMI components or components;
- VEMMI component item or items.
"VEMMI element" is a generic name used in this ETS to designate an object, a component or an item.
An example is given in figure 1.
VEMMI Object
Text Label: Text Input I
VEMMI component item
VEMMI component
VEMMI object
Figure 1: Example showing objects/components/items
4.2.1 VEMMI object definition
VEMMI objects are the logical units which are used by a VEMMI application to interact with the user.
VEMMI objects are composed of different components.
The objects are only defined regarding their functionality, their size and position relative to the Defined
Display Area (DDA). The representation of the objects is terminal dependent.
Every object shall be identified by an Object Identification Number (OIN) which shall be unique within a
VEMMI application at any one time.
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ETS 300 382: February 1995
4.2.2 VEMMI component definition
VEMMI components always belong to a VEMMI object and are only valid within this object. The object, to
which a component belongs, is named "parent object".
In order to transport information, components may carry a data content which can be text or Videotex data
(see subclause 4.5).
The components are only defined regarding their functionality, their type of content and their size and
position relative to the object. The representation of the components, and of their text content, is terminal
dependent. The representation of Videotex content is defined in the corresponding Videotex ETSs
referenced in clause 2.
Every component shall be identified by a Component Identification Number (CIN) which shall be unique
within an object.
4.2.3 VEMMI component item definition
The sub-unit of a VEMMI component is a component item. Every item is an integral part of a component.
The definition of a component item is only valid within this component.
4.3 VEMMI logical plane structure model
A VEMMI logical plane structure model is used to handle VEMMI objects and their contents, as well as
standard Videotex data. The VEMMI logical plane structure model is described below and is presented in
figure 2, with an example of a possible VEMMI terminal structure.
A VEMMI terminal shall implement the behaviour of this VEMMI logical plane structure model. However,
no assumption is made on the real physical plane structure of the terminal and how the terminal
implements that plane structure model. The possible VEMMI terminal structure drawing as shown in figure
2 is for explanatory purposes only.
VEMMI Local Manager
User interactions
(keyboard,mouse,.)
Protocols
Standard
Standard
.
VTX
VTX
.
Standard VTX Data VTX logical plane
Text Display
Data
and
Memory
Layer 7 and
VEMMI objects
VTX
VEMMI Decoders logical plane
(NOTE)
Object
Data
Switcher
VEMMI
Off
Object
Data
VEMMI VEMMI
On
Object Display
Off
Data Memory
Base
On
VEMMI On/Off
VEMMI On/Off
Data flows
Controls
NOTE: Standard Videotex protocols including SBV based protocols or protocols amended for
VEMMI mode as defined in clause 5.
Figure 2: Example of possible VEMMI terminal structure
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ETS 300 382: February 1995
The VEMMI logical plane structure model is based on two logical planes:
- a standard Videotex logical plane;
- a VEMMI objects logical plane.
These two logical planes are fully superimposed (same DDA dimensions and positions).
4.3.1 The standard Videotex logical plane
This logical plane receives standard Videotex data in a background plane. Standard Videotex data are
received from standard Videotex applications or from VEMMI applications using standard Videotex data.
This standard Videotex logical plane shall continue to support the Videotex data rules and priorities
defined in the Videotex ETSs referenced in clause 2.
4.3.2 The VEMMI objects logical plane
This logical plane receives VEMMI objects described in this ETS, and their text and Videotex encoded
data contents. This VEMMI objects logical plane is a foreground plane, with the highest visual priority over
the standard Videotex logical plane. When empty, this plane is fully transparent. When not empty, DDA
areas used by VEMMI objects hide the corresponding parts of the standard Videotex logical plane. Full
transparency for this VEMMI objects logical plane is also possible within a VEMMI application through a
VEMMI command. The VEMMI objects logical plane shall be able to handle object overlapping and
restoring mechanisms as referenced in subclauses 4.6 and 4.11.1. Within this plane, and for a given
VEMMI element Videotex content, the Videotex data rules and priorities defined in the Videotex ETSs
referenced in clause 2 apply.
4.4 Operation modes for VEMMI terminals
Regardless of the current operation mode of the terminal, it shall always provide specific tools to manage
the Videotex specific functions (disconnect, etc.).
4.4.1 The standard Videotex mode
This is the initial mode of operation of a VEMMI terminal when powered on or reset.
In standard Videotex mode, the VEMMI terminal displays standard Videotex data in the standard Videotex
logical plane. Standard Videotex data are fully visible; the VEMMI object logical plane is transparent. User
inputs are not controlled by the VEMMI local manager.
VEMMI On/Off switches are set to the Off position. The terminal shall ignore all VEMMI commands except
VEMMI_On, VEMMI_Create_Object and VEMMI_Open_Object. These last two commands shall perform,
in addition to their normal behaviour, an implicit switch to the VEMMI mode; VEMMI On/Off switches are
then switched to the On position. A VEMMI_Open_Object referring to a non-existing object shall only
induce an object request but shall not switch the terminal to the VEMMI operation mode.
4.4.2 The VEMMI mode
In the VEMMI mode, a VEMMI terminal can receive standard Videotex data and VEMMI objects data in
two parallel paths, as shown in figure 2. The VEMMI On/Off switches are set to the On position.
VEMMI object data are displayed in the VEMMI objects logical plane. Standard Videotex data are
displayed in the Standard Videotex logical plane. VEMMI object displayed in the VEMMI objects logical
plane hide the corresponding parts of the standard Videotex logical plane. The display order for objects
and for components within objects, shall correspond to their transmission order (last received, last
displayed).
User inputs are controlled by the VEMMI local manager.
The display priority rules between the two planes, as defined in subclause 4.3, apply.
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ETS 300 382: February 1995
4.4.3 Switching between standard Videotex mode and VEMMI mode
A standard Videotex Application shall be performed on a VEMMI terminal without any specific command,
only if the application is compatible with the capabilities of the terminal identified with its Terminal Facility
Identifier (TFI). A VEMMI terminal shall always be set in the standard Videotex mode, or Videotex mode,
when powered on, or when physically reset.
From the standard Videotex mode, a VEMMI terminal shall be switched to the VEMMI operation mode,
setting the logical VEMMI On/Off switches to the On position, if one of the following VEMMI commands is
received:
- VEMMI_On;
- VEMMI_Create_Object;
- VEMMI_Open_Object referring to an existing object in the terminal.
If a VEMMI_Open_Object referring to a non-existing object is received, the VEMMI terminal shall request
it from the VEMMI application without switching to the VEMMI mode.
When switched to the VEMMI operation mode the VEMMI terminal shall display standard Videotex data in
the Videotex logical background plane. Additionally, it shall display in the VEMMI objects logical plane:
- VEMMI Open objects still present in the Object data base before the VEMMI operation mode
switching and coming from a previous VEMMI operation mode;
- VEMMI data received since this VEMMI operation mode switching.
Switching to the VEMMI operation mode or switching back does not reset:
- any data within the terminal standard Videotex data path;
- standard Videotex data reception and handling continues;
- any data within the terminal VEMMI object data base.
When a VEMMI_Off command is received, the VEMMI terminal shall switch in the standard Videotex
operation mode and shall display only the standard Videotex logical plane. The VEMMI On/Off switches
are set by the VEMMI_Off command to the Off position; the VEMMI objects logical plane then becomes
fully transparent. The VEMMI_Off command does not reset any data within the VEMMI object data base.
VEMMI object reception and handling in the VEMMI data base then stops, except for the VEMMI_Reset
command and the three commands to switch back to the VEMMI operation mode.
4.5 VEMMI elements data content
For the time being VEMMI elements are able to carry two different types of data content:
a) text data;
b) Videotex data.
For future versions of VEMMI some other types of data content may be available (bitmaps,
...
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