BS ISO/IEC ISP 11184-1:1995 Information technology. International Standardized Profiles. Part 1. FVT1nn. Virtual Terminal Basic Class. Register of VTE-profiles
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1.1 General
The concept of Profiles for OSI, and the structure of the International Standardized Profiles that document them, are defined in ISO/IEC TR 10000-1. Such Profiles are divided into a number of different classes and sub-classes. Two of these classes contain sub-classes comprising functions of the Virtual Terminal Basic Class Service and Protocol specified in the base standards ISO 9040 and ISO 9041. These are the Application Profiles (A-Profiles) and the Interchange Format and Representation Profiles (F-Profiles).
The relationship between A-Profiles and F-Profiles is described in 7.3.2 of ISO/IEC TR 10000-1 and is as follows. Application Layer base standards require, implicitly or explicitly, the structure of information carried or referenced by them to be specified for each instance of communication. It is the purpose of F-Profiles to specify such information structures. Particular functional requirements may then be met by the combination of an A-Profile with one or more F-Profiles.
The Virtual Terminal Basic Class Service and Protocol applies to applications requiring interactive communication with terminal systems through the transmission and manipulation of graphical images composed of character-box graphic elements. Through the selection by negotiation of various options, it may be used to realise a wide range of distinct functions. This process of negotiation involves the selection of a set of VT functional units together with a particular Virtual Terminal Environment profile (VTE-profile) and particular values for any arguments of that VTE-profile.
The specification of a VTE-profile and the permitted values for its arguments may themselves reference other types of object defined in accordance with ISO 9040. These are VT control object types and assignment types. The VTE-profiles, control object types and assignment types are thus information structures that require explicit reference within the VT protocol. Particular instances of these structures are fully defined within the base standards, but the base standards also provide for further instances to be defined by registration. Each registered instance constitutes an F-Profile within the framework of ISO/IEC TR 10000. The specification of the selection of options required to realise a particular function and to promote interoperability constitutes a Virtual Terminal A-Profile within the framework of ISO/IEC TR 10000.
The three International Registers of VT information structures and the specifications of VT Application
Profiles are each published as a separate multi-part ISP as follows:
— ISO/IEC ISP 11184 is the Register of VTE-profiles;
— ISO/IEC ISP 11185 is the Register of control object type definitions;
— ISO/IEC ISP 11186 is the Register of assignment-type definitions;
— ISO/IEC ISP 11187 contains the specifications of VT Application Profiles.
This part of ISO/IEC ISP 11184 contains the specifications of the S-mode Forms and Paged VTE-profiles, both of which operate in the synchronous mode of the Virtual Terminal Service. These VTE-profiles make use of the ability of the Virtual Terminal Service to provide a display object with a structure of fields that have associated entry controls. This structure enables an application process to provide comprehensive facilities for local processing during data entry by a terminal. Such delegation to the terminal of the control of data entry may reduce significantly the demands placed on the application end system and the communication network and may substantially improve the response time to users’ actions.
The Forms and Paged VTE-profiles differ in only one respect. The Paged VTE-profile provides a facility for the terminal to notify the application end system that its capability to process the field structure of the display object is restricted. This facility is not present in the Forms VTE-profile.
NOTE It is intended that applications which use the Paged VTE-profile should be capable of use with terminal end systems based on real block-oriented, as distinct from character-oriented, terminals. Certain real block-oriented terminals implement a field handling mechanism in hardware in a manner that prevents a character being displayed in the character-box display element immediately preceding a field. The additional facility in the Paged VTE-profile enables a terminal to notify the application end system that it is of this type.
This specification includes Profile Requirements Lists (Profile RLs) for the S-mode Forms and Paged VTE-profiles in compliance with the relevant requirements, and in accordance with the relevant guidance, given in ISO/IEC 9646-7. These RLs apply to the PICS proforma for the VT protocol that is given in ISO/IEC 9041-2. They provide constraints on the answers that may be given in that proforma for an implementation of the VT protocol which claims to support the VTE-profile concerned.
1.2 Position within the taxonomy The taxonomy of International Standardized Profiles for OSI is laid down in ISO/IEC TR 10000-2. Within the classification scheme of this taxonomy, the OSI Profiles specified in this International Standardized Profile are in the Virtual Terminal Registered Object sub-class of the class of Interchange Format and Representation Profiles.
A Profile within this subclass has a Profile identifier of the form FVTabc, where abc is a structured numerical identifier that identifies the position of the Profile within each of the three levels of subdivision of the subclass. The values of a and b are single digits but c is an integer that is not necessarily a single digit.
In principle the ISO Virtual Terminal model allows for multiple classes of operation, although at the time of publication of this International Standardized Profile only the Basic Class has been defined. The value of the identifier component a distinguishes between distinct types of information object as follows:
— a = 1 for Basic Class VTE-profiles;
— a = 2 for Basic Class Control Objects;
— a = 3 for Basic Class Assignment Types.
Values of a greater than 3 are reserved for future developments.
ISO/IEC ISP 11184 contains the specifications of the Profiles with identifiers of the form FVT1bc. For this form of identifier, the component b distinguishes between the two modes of operation of the Virtual Terminal Service as follows:
— b = 1 for A-mode (asynchronous mode) operation;
— b = 2 for S-mode (synchronous mode) operation.
Values of b greater than 2 are reserved for new modes of operation that may be defined in future amendments to ISO 9040. The identifier component c distinguishes between different VTE-profiles with the same mode of operation. The procedures of ISO/IEC 9834-4 require a single register of VTE-profiles to be maintained without regard to their mode of operation. The value of the component c is therefore not directly related to the serial number of the VTE-profile in the register.
This part of ISO/IEC ISP 11184 contains the specifications of the VTE-profiles with the Profile identifiers FVT121 — S-mode Forms VTE-profile;
FVT122 — S-mode Paged VTE-profile.
Data processing; Data transmission methods; Conformity; Synchronous transmission; Application layer (OSI); Computer terminals; Data transmission; Computer networks; Communication procedures; Data transfer; Open systems interconnection
BS ISO/IEC ISP 11184-1:1995 Information technology. International Standardized Profiles. Part 1. FVT1nn. Virtual Terminal Basic Class. Register of VTE-profiles
