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7 Town
8 Postcode
9 Date
10 Time
11 Date and time
Note - Local hosts which do not support system fields regard all system fields as marked with a zero value.
If on the other hand an external host does not support system fields, local hosts requiring this attribute are
defaulting the value of the field-type attribute to "0".
10.2.9.3Protected
This attribute is only meaningful for system fields. For those local hosts which are not able to process system
fields, this attribute is not taken into account.
This attribute indicates whether or not the system field may be modified by the user. The value "yes" indicates that
the local host must prevent the user from modifying the contents of the field.
10.2.9.4Data-source
This attribute is only meaningful when the field-type attribute is used, the value is not equal to "0" and the
protected attribute has the value "not protected".
This attribute can have the values "local host" and "user" to indicate whether the data returned to the external host
was supplied by the local host or by the user.
10.2.9.5Field-text-marking
This attribute specifies the visual appearance on the terminal of the contents of the field. The following values
have been identified:
a) "explicit" means that a value for one or more of the following attributes:
- foreground colour;
- background colour;
- underlining;
- flashing;
- reverse video;
may explicitly be defined by the external host.
b) "keep current attributes" means that the value of the foreground colour, background colour, underlining,
flashing and reverse video are then those naturally defined by positioning the cursor in the field.
In both cases, this attribute is applied by the local host as far as possible but the local host may ignore it.
10.2.10Field content portion
This content portion is used when data entry type 2 is selected. The field content portion makes use of the
attribute operational element content type (see Recommendation T.441, or Annex A of Recommendation T.541) as follows:
10.2.10.1Type of coding
This attribute may be set either by the external or local host and specifies the coding used to represent the content
and may take one of the following values:
- T.50 (IRV);
- T.51 "plus space"
The field content portion makes use of the attribute operational element content (see Recommendation T.441, or
Annex A of Recommendation T.541) as follows:
Fascicle VII.7 - Rec. T.564 1
10.2.10.2Content information
This attribute may be set either by the external or by the local host and represents the contents of the field. The
correspondence between the content information and the different field- blocks of the field is given by the defined order of
these field-blocks in the layout attribute of the FIELD-SE, regardless of the relative position of these parts with respect to the
screen.
When set by the external host, this attribute represents the initial content of the field.
When set by the local host, this attribute represents the data entered by the user.
10.2.11DATA-ENTRY-SUBPROGRAM-SE
The DATA-ENTRY-SUBPROGRAM-SE is subordinate to the DATA-ENTRY-PROGRAM-SE. Each data entry
subprogram applies to one and only one field. There are as many subprograms as fields in the form; consequently,
depending on the complexity of the form, one or more data entry subprograms may be defined at the same time.
The following attributes are mapped to the reference attribute defined in Recommendation T.441 (or in Annex A to
Recommendation T.541).
10.2.11.1Reference-to-a-RULES-SE
This attribute points to a RULES-SE. This attribute cannot take the value "undefined" and must be defined either
explicitly or via the default value list mechanism.
Remark on the use of prompts
Prompts are guidance messages that may be associated with each data entry subprogram and are described by
the corresponding PROMPT-SEs. Zero, one or two prompts may be associated with each data entry subprogram. If no
prompt is associated, both of the relevant reference attributes will not be defined and no prompt message is to be displayed.
It is up to the external host to use only a prompt- in or a prompt-in and a prompt-out. On the other hand some local hosts
may not support the use of a prompt-out and consequently will ignore the relevant attribute and automatically erase the
prompt-in. 10.2.11.2Reference-to-a-PROMPT-IN-SE
This attribute set by the external host points to a PROMPT-SE which is displayed by the local host when this data
entry subprogram starts. This attribute may be set to undefined if no prompt-in message is to be displayed.
10.2.11.3Reference-to-a-PROMPT-OUT-SE
This attribute set by the external host points to a PROMPT-SE which is displayed by the local host when this data
entry subprogram is stopped. This attribute may be set to undefined if no prompt- out message is to be displayed.
Using a prompt-in and a prompt-out instead of one prompt has not been finally discussed. This is for further study.
10.2.11.4Reference-to-a-FIELD-SE
The value of this attribute depends on the type of the data entry subprogram concerned (information retrieval, data
collection or data entry "on-the-fly" or duplex data entry). When defined, it indicates the area in which input characters have
to be echoed.
The application defined attributes of the data entry subprogram are the following:
10.2.11.5Echo
This attribute set by the external host specifies the type of echo to be performed by the local host. It may take one
of the three values:
- normal echo: the input character is echoed;
- fixed echo: a fixed character is displayed;
- null: no echo is performed.
10.2.11.6Echoed character
This attribute set by the external host and taken into account only if the echo attribute is set to "fixed echo". This
attribute specifies a character from the list described in Recommenda- tion T.51 "plus space".
2 Fascicle VII.7 - Rec. T.564
10.2.11.7Echoed parameter
This attribute set by the external host specifies the videotex attributes which should apply to the echo, if any. This
attribute may specify values for one or several of the following attributes: foreground colour, background colour, underline,
echo size (normal size, double high, double width, double size), flashing and reverse video.
This attribute is applied by the local host as far as possible, but the local host may ignore it.
10.2.12RULES-SE
This SE is subordinate to the DATA-ENTRY-SE. It describes the rules applicable to the entry in a field: list of
allowed characters, list of authorized retrieval functions, etc.
The application defined attributes of the RULES-SE are the following:
10.2.12.1Time-out
This attribute set by the external host defines the maximum time allowed to the user to enter data. The length of
time is measured in seconds. Value 0 indicates that there is no time limit imposed in seconds. Value 1 is reserved for data
entry type 1 and will be interpreted by some external hosts as a request for chained frames. A value 1 should be interpreted
by the local host as a normal time-out. some local hosts may overwrite with their own value a time-out whose value is
greater than 1.
Expiration of time-out provokes termination of the data entry.
10.2.12.2Entry-invoke-character
This attribute set by the external host defines how the empty positions of the field are filled after displaying the
initial contents. The following value is identified:
- a fixed character from T.51 plus the character "space".
The visual appearance of the entry-invoke-character is controlled by the field-text-marking attribute. These
characters are not entered in the field content portion and not reported to the external host.
10.2.12.3Local editing
This attribute set by the external host indicates that powerful editing capabilities should be performed in the
associated field. Such a local editing capability defined by the local host, would allow to insert/delete character/word/line,
powerful cursor movement, etc. This local editing facility is intended to be used by applications dealing with message
handling.
Remark on the control of the user input
In the general situation of an international videotex interworking the following attributes (from 10.2.12.4 to
10.2.12.7), specified to allow local hosts to control the users input, may not be supported by some local hosts. In those
cases no checking of the relevant attributes will be performed by the local host.
10.2.12.4Length of valid choices
This attribute may take the value 1 or 2 depending on the size of the choice (one or two digits). This attribute is
used only in data entry type 1 and not taken into account if the D1 c command is disabled.
10.2.12.5List-of-enabled-choices
This attribute is set by the external host and specifies the list of enabled choices. This attribute is not taken into
account by the local host if the D1 c command is disabled. This attribute is used only in data entry type 1.
10.2.12.6Allowed-characters (for data collections)
This attribute set by the external host indicates if the list of characters represents the allowed or forbidden
characters.
Possible values:
- "allowed": means allowed characters in the list;
- "not allowed": means forbidden characters in the list;
Fascicle VII.7 - Rec. T.564 3
- "alphabetic": only alphabetic characters may be entered;
- "alphanumeric": only alphanumeric characters may be entered;
- "numeric": only numeric characters may be entered.
When this attribute does not have the value "allowed" or "not allowed", the character-list attribute must not be used
or will be ignored.
This attribute is only used in data-entry-type 2.
10.2.12.7Character-list (for data collection)
List of characters according to the specified set in the type of coding attribute of the FIELD-SE. This attribute is set
by the external host. It specifies the list of characters which may or may not be entered as user inputs in the field associated
with the DATA-ENTRY-SUBPROGRAM-SE from which the RULES-SE is referred. The list of characters is encoded according
to T.51 plus "space".
This attribute is only used in data-entry-type 2.
10.2.12.8List of valid commands
This attribute set by the external host specifies the list of commands which are enabled and then may be used as
values for the termination reason attribute of the RESULT-SE. Other commands are disabled and cannot be used as value
for the termination-reason attribute. However, enabling of commands does not imply that the local host is forced to support all
the enabled commands. It is up to the local host to do its best to properly image some commands. Some local hosts may
transform some commands into a disconnect.
Abbreviations:
E: Enabled
D: Disabled
Y: Yes
N: No
CP: Indicates if a result content portion may be associated with the command
local: Functions handled locally between the user and the local host; such functions are not exchanged on
the international link between gateways. Some functions of this type may provoke a disconnect
between the local and the external host.
not used: Not used for a given type of data entry.
Note - Further development of videotex interworking may identify a requirement to use also the commands V1, V4,
V7 on the international link. This is for further study.
The following list defines the valid commands taken from the list of functions defined by Recommendation F.300.
a) Type 1: Information retrieval
Termination reason Command LocalCP
E/D
- Select an application on a videotex service V1 Y
- Leave the application and return to the first
effective choice of the national videotex V2 N N E/D
service (see Note 1)
- Return to the first effective choice of the V3 N N E
foreign videotex service
- Leave the application and return to the point V4 Y
from which this application was selected
- Provide billing information V5 Y
- Leave the videotex service (mandatory) V6 Y
(see Note 2)
4 Fascicle VII.7 - Rec. T.564
- Request service/application Id V7 Y
Fascicle VII.7 - Rec. T.564 5
- Declare and validate an input (see Note 3) D1
a) free text input a) N YE/D
b) direct selection of a frame b) N YE/D
c) progress through a choice from one frame c) N YE/D
to another by the use of one or two digits
d) select a frame through the use of a keyword d) N YE/D
- Correcting an input D2 Y
- Clearing an input D3 Y
- Move one step forward in the application D4 N N E/D
- Move to the next input field D5 -- not
used --
- Retrace the previous step D6 N N E/D
- Move to the previous field D7 -- not
used --
- Repeat the frame D8 Y
- Repeat the updated frame D9 N N E/D
- Return to the first menu in the application D10 N N E/D
- Previous menu D11 N N E/D
- Ask for help or guidance without leaving the D12 N N E/D
application
- Redisplay the initial version of the currently D13 N N E/D
active form
- Redisplay the completed version of the D14 N N E/D
currently active form
- Interrupt the action in progress D15 Y
- Set a marker at the current point in the D16 Y
application for access at a later time within
the same session
- Abstain from forwarding the contents of the D17 -- not
used --
input field
- Declare valid a "set" of inputs D18 -- not
used --
- Time out (see Note 4) N N E
- End of field -- not
used --
Note 1 - If this command is not supported by the local host or if this command is disabled, then the
6 Fascicle VII.7 - Rec. T.564
corresponding local command is mapped to a D-TERMINATE.
Note 2 - This command is directly mapped to a D-TERMINATE.
Note 3 - Some local hosts may not be able to make the difference between the four D1 sub-commands
and consequently may replace D1 b, D1 c and D1 d by D1 a, even if disabled.
Note 4 - The time-out is disabled by setting its value to 0.
Remark on the use of "good-by" frames
1) The local host does not support the use of "good-by" frames: in this case the local host maps the
local V2 command to a D-TERMINATE req. on the international connection.
2) The external host does not support the use of "good-by" frames: in this case the external host
should disable the V2 command and the local host consequently maps a local V2 command to a D-
TERMINATE req. on the international connection.
Fascicle VII.7 - Rec. T.564 7
3) Both hosts are supporting the use of "good-by" frames: in this case the external host enables the
V2 command. If the local host sends a V2 command to the external host, the external host may
send the "good-by" frame, followed by a D-TERMINATE req.
b) Type 2: Data collection
Termination reason Command LocalCP
E/D
- Select an application on a videotex service V1 Y
- Leave the application and return to the first
effective choice of the national videotex V2 N N E/D
service (see Note 1)
- Return to the first effective choice of the V3 N N E
foreign videotex service
- Leave the application and return to the point V4 Y
from which this application was selected
- Provide billing information V5 Y
- Leave the videotex service (mandatory) V6 Y
(see Note 2)
- Request service/application Id V7 Y
- Declare and valid an input (see Note 3) D1
a) free text input a) N YE/D
b) direct selection of a frame b) N YE/D
c) progress through a choice from one frame c) -- not
used --
to another by the use of one or two digits
d) select a frame through the use of a keyword d) N YE/D
- Correcting an input D2 Y
- Clearing an input D3 Y
- Move one step forward in the application D4 N N E/D
- Move to the next input field D5 N N E/D
- Retrace the previous step D6 N N E/D
- Move to the previous field D7 N N E/D
- Repeat the frame D8 Y
- Repeat the updated frame D9 N N E/D
- Return to the first menu in the application D10 N N E/D
- Previous menu D11 N N E/D
- Ask for help or guidance without leaving the D12 N N E/D
application
- Redisplay the initial version of the currently D13 N N E/D
active form
- Redisplay the completed version of the D14 N N E/D
currently active form
- Interrupt the action in progress D15 Y
- Set a marker at the current point in the D16 Y
application for access at a later time within
the same session
- Abstain from forwarding the contents of the D17 N N E/D
input field
- Declare valid a "set" of inputs D18 N N E/D
8 Fascicle VII.7 - Rec. T.564
- Time out (see Note 4) N N E
- End of field N N E/D
Fascicle VII.7 - Rec. T.564 9
Note 1 - If this command is not supported by the local host or if this command is disabled, then the
corresponding local command is mapped to a D-TERMINATE.
Note 2 - This command is directly mapped to a D-TERMINATE.
Note 3 - Some local hosts may not be able to make the difference between the four D1 sub-commands
and consequently may replace D1 b, D1 c and D1 d by D1 a, even if disabled.
Note 4 - The time-out is disabled by setting its value to 0.
Remark - See also remark to data-entry type 1.
c) Types 3 and 4: Data entry on the fly/duplex data entry
Termination reason Command LocalCP
E/D
- Select an application on a videotex service V1 Y
- Leave the application and return to the first
effective choice of the national videotex V2 N N E/D
service (see Note 1)
- Return to the first effective choice of the V3 N N E
foreign videotex service
- Leave the application and return to the point V4 Y
from which this application was selected
- Provide billing information V5 Y
- Leave the videotex service V6 Y
(see Note 2) (mandatory)
- Request service/application Id V7 Y
- Declare and valid an input (see Note 3) D1
a) free text input a) N YE/D
b) direct selection of a frame b) -- not
used --
c) progress through a choice from one frame c) -- not
used --
to another by the use of one or two digits
d) select a frame through the use of a keyword d) -- not
used --
- Correcting an input D2 Y
- Clearing an input D3 Y
- Move one step forward in the application D4 N N E/D
move to the next input field D5 -- not
used --
- Retrace the previous step D6 N N E/D
- Move to the previous field D7 -- not
used --
- Repeat the frame D8 Y
- Repeat the updated frame D9 N N E/D
- Return to the first menu in the application D10 N N E/D
- Previous menu D11 N N E/D
- Ask for help or guidance without leaving the D12 N N E/D
application
- Redisplay the initial version of the currently D13 N N E/D
10 Fascicle VII.7 - Rec. T.564
active form
- Redisplay the completed version of the D14 N N E/D
currently active form
- Interrupt the action in progress D15 Y
Fascicle VII.7 - Rec. T.564 11
- Set a marker at the current point in the D16 Y
application for access at a later time within
the same session
- Abstain from forwarding the contents of the D17 N N E/D
input field
- Declare valid a "set" of inputs D18 -- not
used --
- Time out (see Note 3) N N E
- End of field N N E/D
Note 1 - If this command is not supported by the local host or if this command is disabled, then the
corresponding local command is mapped to a D-TERMINATE.
Note 2 - This command is directly mapped to a D-TERMINATE.
Note 3 - Time-out is disabled by setting its value to 0.
Remark - See also remark to data-entry type 1.
10.2.12.8.1 Specification of local characteristics
Within the national videotex service of country A the user may enter commands which are:
- disabled by the external host;
- specified as local in the list of valid commands;
- or not used in a specific type of data entry.
As these commands may not be passed to the external host, the following list describes the behaviour a local host
should perform when receiving such a command:
V1: Select an application on a videotex service
Local action
V2: Leave the application and return to the first effective choice of the national videotex service
Enabled: send to the EH or D-TERMINATE
Disabled: D-TERMINATE
V3: Return to the first effective choice of the foreign videotex service
Enabled: send to the EH
Disabled: local error indication
V4: Leave the application and return to the point from which this application was selected
Local action
V5: Provide billing information
Local action
V6: Leave the videotex service
D-TERMINATE
V7: Request service/application id
Local action
D1: Declare and valid an input
Enabled: send to the EH
Disabled: local error indication
D2: Correcting an input
Local action: delete the character, if any
D3: Clearing an input
Local action: delete the current field content and restart the current input
D4: Move one step forward in the application (typically Next or # on the last field)
Enabled: send to the EH
Disabled: local error indication
12 Fascicle VII.7 - Rec. T.564
D5: Move to the next input field
Enabled: send to the EH
Disabled: move to the next field if any
Fascicle VII.7 - Rec. T.564 13
D6: Retrace the previous field
Enabled: send to the EH
Disabled: local error indication
D7: Move to the previous field
Enabled: send to the EH
Disabled: move to the previous field if any
D8: Repeat the frame
Local action: redisplay the display structure and the content of the data entry structure (field contents and
prompts) then restart the data entry at the interrupted point
D9: Repeat the updated frame
Enabled: send to the EH
Disabled: local error indication
D10: Return to the first menu in the application
Enabled: send to the EH
Disabled: local error indication
D11: Previous menu
Enabled: send to the EH
Disabled: local error indication
D12: Ask for help or guidance without leaving the application
Enabled: send to the EH
Disabled: local error indication
D13: Redisplay the initial version of the currently active form
Enabled: local error indication. (When no user input has been transmitted to the external host, also other
local actions may be taken)
D14: Redisplay the completed version of the currently active form
Enabled: send to the EH
Disabled: local error indication
D15: Interrupt the action in progress
Local action
D16: Set a marker at the current point
For further study
D17: Abstain from forwarding the content (abort data collection)
Enabled: send to the EH
Disabled: local error indication
D18: Declare valid a set of inputs
Enabled: send to the EH
Disabled: local error indication
- : End of field
Enabled: send to the EH
Disabled: move to the next field if any, otherwise local error indication
- : Time-out
Enabled: send to the EH
Disabled: no action
10.2.12.8.2Use of the information retrieval field in data collection
In some videotex services, some userw's keying action (e.g. * or Next) may automatically provoke, even in a data
entry subprogram, the termination of the filling of the current field and a cursor movement to the information retrieval field
where a retrieval command may be entered. Such a command, once completed, will be interpreted as a termination event by
the local host and reported back to the external host as a termination reason.
14 Fascicle VII.7 - Rec. T.564
Moreover, in the case of a direct access or keyword command, an associated text is also to be reported to the
external host, setting the termination-reason-text attribute of the DATA-ENTRY- PROGRAM-SE.
There is not a DATA-ENTRY-SUBPROGRAM-SE present in the VIA for the information retrieval field when "data-
collection-type" has been selected. This includes that the RULES-SE of the last data collection field, the user has "touched",
before going to the information retrieval field, is to be used also for the information retrieval field.
10.2.13PROMPT-SE
The PROMPT-SE is subordinate to the DATA-ENTRY-SE. The attributes of a PROMPT-SE are those of a BLOCK-
SE, except for the SE-type which is PROMPT. A prompt is a message to be displayed to the user for guidance by the filling
of a field.
The prompt referred from a DATA-ENTRY-SUBPROGRAM-SE is automatically displayed when the data entry
subprogram becomes active. The prompt is cancelled by the local host when the associated data entry subprogram becomes
inactive i.e. when another data entry subprogram becomes active or when the data entry program is terminated.
The cancelled prompt text on the screen must be replaced by a new prompt text and/or by "spaces".
The application defined attributes of a PROMPT-SE are the following (as defined for the display structure):
10.2.13.1Position
10.2.13.2Dimensions
10.2.14Prompt content portion
The prompt content portion makes use of the attributes operational element identifier, operational element content
type, operational element content (see Recommendation T.441, resp. Annex A of Recommendation T.541) as the related
attributes for content portions (defined in Recommendation T.412) are used for blocks.
The application defined attributes for prompt is the following:
10.2.14.1Coding attributes
This attribute is used in the same way as for blocks, it is specified within Recommenda- tion T.412.
10.2.15Application control memory structure
The application control memory structure can be used to store any operation on the VIA, for example:
- the display structure or parts of it (e.g. create BLOCK-SE or modify FIELD-SE) or parts of it;
- the data entry structure or parts of it;
- the administrative structure or parts of it;
- the special terminal facilities structure or parts of it.
An element from the application control memory is invoked by a D-CALL operation and applied to the VIA, if
applicable, in both hosts.
The application control memory structure consists of:
- the APPLICATION-CONTROL-MEMORY-SE;
- one or more RECORD-SEs subordinate to the APPLICATION-CONTROL-MEMORY-SE.
The RECORD-SE contains a sequence of one or more of the operations: D-CREATE, D-DELETE, D-MODIFY,
which do not concern SEs of the application control memory structure.
Figure 7/T.564 describes the hierarchy of the application control memory structure constituents.
Fascicle VII.7 - Rec. T.564 15
FIGURE 7/T.564
10.2.16APPLICATION-CONTROL-MEMORY-SE
10.2.17RECORD-SE
The application defined attributes of the RECORD-SE are the following:
10.2.17.1Record content
This attribute consists of a list of VIA operations which do not concern the RECORD-SE or the APPLICATION-
CONTROL-MEMORY-SE.
Details are depending on the ongoing work on operational structures.
10.3 Administrative structure
Note - This section is provisional. Final version will be established taken into account the results of CCITT Study
Groups I and III concerning videotex administrative and charging matters.
10.3.1 Overview of the administrative structure
This structure is used for exchanging supervisory information such as:
- items subject to negotiation (e.g. limits);
- accounting information;
- global information related to the state of the association;
- global information related to the document transferred.
This structure consists of the ADMINISTRATIVE-INFORMATION-SE which has three subordinates:
- LOCAL-HOST-INFORMATION-SE;
- EXTERNAL-HOST-INFORMATION-SE;
- DOCUMENT-INFORMATION-SE.
One and only one SE of each type should exist within the administrative structure (see Figure 8/T.564).
FIGURE 8/T.564
16 Fascicle VII.7 - Rec. T.564
10.3.2 ADMINISTRATIVE-INFORMATION-SE
This SE contains information pertinent throughout the whole association.
This SE makes use of the following application defined attributes:
10.3.2.1External host Id
This attribute identifies the external host to be connected to.
10.3.2.2Local host Id
This attribute identifies the originating host.
10.3.2.3Bilateral management parameter
This attribute is reserved for information which is exchanged between the two gateways and can be based on
bilateral agreement.
10.3.3 LOCAL-HOST-INFORMATION-SE
This element is used to transfer information from the local host to the external host.
This element makes use of the following application defined attribute:
10.3.3.1Error report to external host
This attribute is used to indicate to the external host the reason why the local host could not handle the previously
received reply.
10.3.4 EXTERNAL-HOST-INFORMATION-SE
This element is used to transfer information from the external host to the local host.
This element makes use of the following application defined attributes:
10.3.4.1Error report to local host
This attribute is used to indicate to the local host the reason why the external host could not handle the previously
received reply.
10.3.4.2Asynchronous message
This attribute is used to transfer a warning message to the local host.
10.3.5 DOCUMENT-INFORMATION-SE
This element contains attributes that supply additional charging information associated with the document and to be
used by the local host.
This element contains the following application defined attributes:
10.3.5.1Application time based charging period
This attribute defines the length of the time base in seconds.
10.3.5.2Application price: frame based
This attribute indicates the frame based price of the application in the currency of the external host.
10.3.5.3Application price: transaction based
This attribute indicates the transaction based price of the application in the currency of the external host.
10.3.5.4Application time based charging price
This attribute defines the price per unit in the currency of the external host.
10.3.5.5Communication cost: time based charging period
The service cost corresponds to the additional cost in the currency of the external host for using a videotex
service. This cost is time dependent. This attribute indicates the value of the period for the service cost. It may depend on
the day and the time (for further study).
Fascicle VII.7 - Rec. T.564 17
10.3.5.6Communication cost: time based charging price
The service cost corresponds to the additional cost in the currency of the external host for using a videotex
service. This cost is time dependent. This attribute indicates the value of the price for the service cost per time unit. It may
depend on the day and the time (for further study).
10.3.6 Items for further study concerning the administrative structure
a) Depending on the decisions of CCITT Study Group III on the interpretation of the item- over-limit facility, the
introduction of an accounting-information-SE might be necessary so that the local host can provide the
external host with limits on the:
- item cost;
- time-based charging;
- session cost;
and the currently translation. This is for further study.
b) The exchange of total session cost at the end of the session, which might be achieved by introducing a
charge-info and a charge-info-request attribute to the LOCAL-HOST-SE and to the EXTERNAL-HOST-SE, is
for further study.
c) Introducing value added taxes is for further study.
d) Using a result parameter is for further study.
e) In addition to a time-based charging for the communication cost, other methods could be taken into account
(i.e. volume oriented). This is for further study.
10.4 Special terminal facilities structure
This special terminal facilities structure is concerned with information which enables the external host to reconfigure
the videotex terminal. The following categories of such information are identified:
- screen format;
- dynamically redefinable character sets (DRCS);
- redefinable colours.
Note - If the local host do not support these categories the structure is not used.
The special terminal facilities structure consists of:
- one SPECIAL-TERMINAL-FACILITIES-SE;
- zero, one or more REDEFINITION-ENTRY-SEs subordinate to the SPECIAL-TERMINAL- FACILITIES-SE.
Terminal redefinition data shall be downloaded by the local host to the videotex terminal, before any blocks or
fields are displayed.
Figure 9/T.564 describes the hierarchy of the special terminal facilities structure.
FIGURE 9/T.564
18 Fascicle VII.7 - Rec. T.564
10.4.1 SPECIAL-TERMINAL-FACILITIES-SE
This element contains the following application defined attributes:
10.4.1.1Measurement unit
This attribute specifies the unit used to express the dimensions attribute of the PAGE-SE. The following value is
identified:
- character box.
10.4.1.2Dimensions
This attribute consists of a pair of coordinates that specify the dimensions of the DDA of the videotex terminal.
These dimensions are expressed in accordance with the measurement-unit attribute.
10.4.2 REDEFINITION-ENTITY-SE
This SE contains the following application defined attribute:
10.4.2.1Redefinition coding
This attribute is subdivided in two parts: it specifies the type and it specifies the syntax used to encode the
redefinition content. The following redefinition types have been identified:
- DRCS;
- colour redefinition.
The following redefinition syntax have been identified:
- interworking data syntax;
- data syntax I;
- data syntax II;
- data syntax III.
10.4.2.2Redefinition content
This attribute contains the actual redefinition data to be downloaded to the userw's terminal. This data will
redefine a terminal facility as identified by the redefinition coding type. It consists of a sequel of bytes coded in accordance to
the value of the redefinition coding attribute.
ANNEX A
(to Recommendation T.564)
This Annex is an integral part of this Recommendation.
This Annex specifies the constituents of the layout structure and of the operational structure which are implicitly
created at connection time.
Profiles:
- document profile;
- operational profile (for further study).
Layout structure:
- specific layout root;
Operational structure:
- data-entry-SE;
Fascicle VII.7 - Rec. T.564 19
- result-SE;
- result-content portion;
20 Fascicle VII.7 - Rec. T.564
- application-control-memory-SE;
- administrative-information-SE;
- local-host-information-SE;
- external-host-information-SE;
- document-information-SE;
- special-terminal-facilities-SE.
Some attributes of these objects are updated at connection time with values carried by parameters of the D-
INITIATE service element (to be detailed).
ANNEX B
(to Recommendation T.564)
This Annex is a provisional part of this Recommendation.
This Annex describes the minimum size of the data structures which must be supported by the local host.
Size of the display and the data entry structures: 2 K bytes;
Size of application control memory structure: FFS;
Number of characters that may be input in the fields: 500;
Number of data entry subprograms: 24;
Number of fields: 24;
Number of rules: 24;
Number of prompts: 24
Number of records: FFS
Fascicle VII.7 - Rec. T.564 21