The concept of Profiles for OSI, and the structure of the Intematlonal
Standardized Profiles that document them, are defined in ISOIIECTR
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
specnied In the base standards ISO 9040 and ISO 9041. These are the
Application Profiles (A-Profiles) and the Interchange Format and
Representallon 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 wilh one or more F¬Profiles.
Establishment of a VT -association Involves the selection by negotiation
of a particular Virtual Terminal Environment profile (VTE-profile), and
of partIcular values for any arguments of that VTE-profile. The VTE-
profile specillcation, and poSSibly also the values of certaIn VTE-
profile arguments, may In turn reference the definilions of VT control
object types and assignment types. These VTE-profiles, control object
types and assignment types are thus information structures that require
explicil reference within the VT protocol. Particular instances of these
structures are fully defined wilhin the base standards, but the base
standards also provide for further instances to be defined by
registration. Each registered instance conslilutes an F-Profile within
the framework of ISOIIEC TR 10000.
The Virtual Terminal Basic Class Service and Protocol may be used to
rea/lse a wide range of distinct functions. Particular functions may be
realised through the selection of appropriate VT functional unils,
F.Profiles and other VTE. profile argument values. The specification of
the selection required to realise a particular function and to promote
interoperebility constilutes a Virtual Terminal A-Profile wilhin the
framework of ISOIIEC TR 10000.
The three International Registers of VT information structures and the
specUlcatlons of VT Application Profiles are each published as a separate multi-part ISP as follows:
- ISOIIEC ISP 11184 is the ReQister of VTE-profiles;
- ISO/IEC ISP 11185 is the Register of control object
- type definitions;
- ISOIIEC ISP 11186 is the Register of assignment.type definitions;
- ISOIIEC ISP 11187 contains the specifications of VT Application Profiles.
This part of ISOIIEC ISP 11185 contains the definition of a control
object type that may be used to set a time limil associated wilh data
entry into the display object during S-mode operalion of a VT -
association. The significance of the expiry of this time limil does not
form pan of this definilion and should be specified by any VTE-profile
that references a control object of this type.