[Federal Register Volume 60, Number 18 (Friday, January 27, 1995)]
[Notices]
[Pages 5362-5368]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-2103]



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DEPARTMENT OF COMMERCE
National Institute of Standards and Technology
[Docket No. 940541-4339]
RIN 0693-AB30


Approval of Federal Information Processing Standards Publication 
153-1, Programmer's Hierarchical Interactive Graphics System (PHIGS)

AGENCY: National Institute of Standards and Technology (NIST), 
Commerce.

ACTION: The purpose of this notice is to announce that the Secretary of 
Commerce has approved a revised standard, which will be published as 
FIPS Publication 153-1, Programmer's Hierarchical Interactive Graphics 
System (PHIGS).

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SUMMARY: On June 17, 1994 (59 FR 31209-31214), notice was published in 
the Federal Register that a revision to Federal Information Processing 
Standard 153, Programmer's Hierarchical Interactive Graphics System 
(PHIGS) was being proposed for Federal use.
    The written comments submitted by interested parties and other 
material available to the Department relevant to the revised standard 
was reviewed by NIST. On the basis of this review, NIST recommended 
that the Secretary approve the revised standard as a Federal 
Information Processing Standards Publication, and prepared a detailed 
justification document for the Secretary's review in support of that 
recommendation.
    The detailed justification document which was presented to the 
Secretary is part of the public record and is available for inspection 
and copying in the Department's Central Reference and Records 
Inspection Facility, Room 6020, Herbert C. Hoover Building, 14th Street 
between Pennsylvania and Constitution Avenues, NW, Washington, DC 
20230.
    This FIPS contains two sections: (1) An announcement section, which 
provides information concerning the applicability, implementation, and 
maintenance of the standard; and (2) a specifications section which 
deals with the technical requirements of the standard. Only the 
announcement section of the standard is provided in this notice.

EFFECTIVE DATE: This revised standard becomes effective August 1, 1995.

ADDRESSES: Interested parties may purchase copies of this revised 
standard, including the technical specifications section, from the 
National Technical Information Service (NTIS). Specific ordering 
information from NTIS for this standard is set out in the Where to 
Obtain Copies Section of the announcement section of the standard.

FOR FURTHER INFORMATION CONTACT:
Mr. Kevin G. Brady, telephone (301) 975-3644, National Institute of 
Standards and Technology, Gaithersburg, MD 20899.

    Dated: January 18, 1995.
Samuel Kramer,
Associate Director.

Federal Information Processing Standards Publication 153-1

(date)

Announcing the Standard for Programmer's Hierarchical Interactive 
Graphics System (PHIGS)
    Federal Information Processing Standards Publications (FIPS PUBS) 
are issued by the National Institute of Standards and Technology after 
approval by the Secretary of Commerce pursuant to Section 111(d) of the 
Federal Property and Administrative Services Act of 1949 as amended by 
the Computer Security Act of 1987, Public Law 100-235.
    1. Name of Standard. Programmer's Hierarchical Interactive Graphics 
System (PHIGS) (FIPS PUB 153-1).
    2. Category of Standard. Software Standard, Graphics.
    3. Explanation. This publication is a revision of FIPS PUB 153 and 
supersedes that document in its entirety. This revision provides a 
substantial, upward-compatible enhancement of the basic PHIGS 
functionality known as Plus Lumiere and Surfaces, PHIGS PLUS (ANSI/ISO 
9592.1a,2a,3a,4:1992). PHIGS PLUS adds facilities for the specification 
of curved lines, curved and faceted surfaces, lighting and shading, and 
adds a mechanism for color specification to allow non-indexed color 
specification. Amendments to each part of the PHIGS specification 
detail revisions required by PHIGS PLUS. Also, each language binding of 
PHIGS has been amended as a result of PHIGS PLUS. The specifications 
and amendments that comprise the complete PHIGS standard as a result of 
this revision are detailed in the Specification section of this 
document.
    In addition this revision adds a requirement for validation of 
PHIGS implementations using either FORTRAN or C bindings. However, 
[[Page 5363]] validation is currently limited to basic PHIGS 
functionality, and therefore does not include the new functionality of 
PHIGS PLUS added by this revision.
    FIPS 153-1 adopts the American National Standard Programmer's 
Hierarchical Interactive Graphics System, ANSI/ISO 9592.1-3:1989, and 
ANSI/ISO 9592.1a,2a,3a,4:1992, and 9593.1:1990, 9593.3:1990, 
9593.4:1991, as a Federal Information Processing Standard (FIPS). This 
standard specifies the control and data interchange between an 
application program and its graphic support system. It provides a set 
of functions and programming language bindings for the definition, 
display and modification of geometrically related objects, graphical 
data, and the relationships between the graphical data. The purpose of 
the standard is to promote portability of graphics application programs 
between different installations. The standard is for use by 
implementors as the reference authority in developing graphics software 
systems; and by other computer professionals who need to know the 
precise syntactic and semantic rules of the standard.
    4. Approving Authority. Secretary of Commerce.
    5. Maintenance Agency. U.S. Department of Commerce, National 
Institute of Standards and Technology (NIST), Computer Systems 
Laboratory (CSL).
    6. Cross Index.
    a. ANSI/ISO 9592.1:1989, Information Processing Systems--Computer 
Graphics--Programmer's Hierarchical Interactive Graphics System 
(PHIGS), Part 1, Functional Description.
    b. ANSI/ISO 9592.1a:1992, Amendment 1, Information Processing 
Systems--Computer Graphics--Programmer's Hierarchical Interactive 
Graphics System (PHIGS), Part 1, Functional Description.
    c. ANSI/ISO 9592.2:1989, Information Processing Systems--Computer 
Graphics--Programmer's Hierarchical Interactive Graphics System 
(PHIGS), Part 2, Archive File Format.
    d. ANSI/ISO 9592.2a:1992, Amendment 1, Information Processing 
Systems--Computer Graphics--Programmer's Hierarchical Interactive 
Graphics System (PHIGS), Part 2, Archive File Format.
    e. ANSI/ISO 9592.3:1989, Information Processing Systems--Computer 
Graphics--Programmer's Hierarchical Interactive Graphics System 
(PHIGS), Part 3, Clear Text Encoding of Archive File.
    f. ANSI/ISO 9592.3a:1992, Amendment 1, Information Processing 
Systems--Computer Graphics--Programmer's Hierarchical Interactive 
Graphics System (PHIGS), Part 3, Clear Text Encoding of Archive File.
    g. ANSI/ISO 9592.4:1992, Information Processing Systems--Computer 
Graphics--Programmer's Hierarchical Interactive Graphics System 
(PHIGS), Part 4, Plus Lumiere and Surfaces, PHIGS PLUS.
    h. ANSI/ISO 9592.1:1990, Information Processing Systems--Computer 
Graphics--Programmer's Hierarchical Interactive Graphics System 
(PHIGS), Language Bindings, FORTRAN.
    i. ISO/IEC 9593.1:1990 Tech. Corrigendum, Programmer's Hierarchical 
Interactive Graphics System (PHIGS), Language Bindings, FORTRAN.
    j. ANSI/ISO 9593.3:1990, Information Processing Systems--Computer 
Graphics--Programmer's Hierarchical Interactive Graphics System 
(PHIGS), Language Bindings, Ada.
    k. ISO/IEC 9593.3:1990, Tech. Corrigendum, Programmer's 
Hierarchical Interactive Graphics System (PHIGS) Language Bindings, 
Ada.
    l. ANSI/ISO 9593.4:1991, Information Processing Systems--Computer 
Graphics--Programmer's Hierarchical Interactive Graphics System 
(PHIGS), Language Bindings, C.
    7. Related Documents.
    a. Federal Information Resources Management Regulations (FIRMR) 
subpart 201.20.303, Standards, and subpart 201.39.1002, Federal 
Standards.
    b. Federal ADP and Telecommunications Standards Index, U.S. General 
Services Administration, Information Resources Management Service, 
(updated periodically).
    c. NIST, Validated Products List: Programming Languages, Database 
Language SQL, Graphics, GOSIP, POSIX, Security, Published quarterly and 
available by subscription from the National Technical Information 
Service (NTIS), U.S. Department of Commerce, Springfield, VA 22161.
    d. FIPS PUB 69-1, Programming Language FORTRAN, adopts ANSI X3.9-
1978/R1989.
    e. FIPS PUB 119, Programming Language Ada, adopts ANSI/MIL-STD-
1815A-1983.
    f. FIPS PUB 120-1, Graphical Kernel System (GKS), adopts ANSI 
X3.124-1985.
    g. FIPS PUB 128-1, Computer Graphics Metafile (CGM), adopts ANSI/
ISO 8632:1992.
    h. FIPS PUB 160, Programming Language C, adopts ANSI/ISO 9899: 
1992.
    i. ANSI/ISO 8632:1992, Information Processing Systems--Computer 
Graphics Metafile for the Storage and Transfer of Picture Description 
Information (Part 1: Functional Specifications; Part 2: Character 
Encoding; Part 3: Binary Encoding; Part 4: Clear Text Encoding).
    j. ISO/IEC 646:1991, Information Processing--7-Bit Coded Character 
Set for Information Interchange.
    k. ISO 2022:1986, Information Processing--ISO 7-Bit and 8-Bit Coded 
Character Sets--Code Extension Techniques.
    l. ISO 2382/13:1984, Data Processing--Vocabulary--Part 13: Computer 
Graphics.
    m. ISO 6093:1985, Information Processing--Representation of Numeric 
Values in Character Strings for Information Interchange.
    n. ISO 7942:1985, Information Processing Systems--Computer 
Graphics--Functional Specification of the Graphical Kernel System 
(GKS).
    o. ISO 7942/Amendment 1:1991, Computer Graphics--Graphical Kernel 
Systems (GKS) Functional Descriptions.
    p. ISO 8805:1988, Information Processing--Computer Graphics--
Graphical Kernel System (GKS-3D) Extensions Functional Description.
    8. Objectives. The primary objectives of this standard are:

--To allow very highly interactive graphics application programs using 
2D or 3D hierarchically structured graphics data to be easily 
transported between installations. This will reduce costs associated 
with the transfer of programs among different computers and graphics 
devices, including replacement devices.
--To aid the understanding and use of dynamic hierarchical graphics 
methods by application programmers.
--To aid manufacturers of graphics equipment by serving as a guideline 
for identifying useful combinations of graphics capabilities in a 
device.
--To encourage more effective utilization and management of graphics 
application programmers by ensuring that skills acquired on one job are 
transportable to other jobs, thereby reducing the cost of graphics 
programmer retraining.
--To aid graphics application programmers in understanding and using 
graphics methods by specifying well-defined functions and names. This 
will avoid the confusion of incompatibility common with operating 
systems and programming languages.

    9. Applicability. PHIGS is one of the computer graphics standards 
(Appendix A discusses the family of computer graphics standards) 
provided for use by [[Page 5364]] all Federal departments and agencies. 
These graphics standards should be used for all computer graphics 
applications and programs that are either developed or acquired for 
government use.
    9.1  The FIPS for PHIGS is intended for use in computer graphics 
applications that are either developed or acquired for government use. 
It is specifically designed to meet the performance requirements of 
such demanding applications as Computer Aided Design/Computer Aided 
Engineering/Computer Aided Manufacturing, command and control, 
molecular modelling, simulation and process control. It emphasizes the 
support of applications needing a highly dynamic, highly interactive 
operator interface and expecting rapid screen update of complex images 
to be performed by the display system. The PHIGS PLUS functionality is 
designed to support graphics applications requiring lighting and 
shading, curved lines, curved and facetted surfaces, and non-indexed 
color specification.
    9.2  The use of this standard is compulsory and binding when one or 
more of the following situations exist:

--The graphics application is very highly interactive, or contains 
hierarchically structured graphics data, or requires rapid modification 
of 2D or 3D graphics data and the relationships among the data.
--It is anticipated that the life of the graphics program will be 
longer than the life of the presently utilized graphics equipment.
--The graphics application or program is under constant review for 
updating of the specifications, and changes may result frequently.
--The graphics application is being designed and programmed centrally 
for a decentralized system that employs computers of different makes 
and models and different graphics devices.
--The graphics program will or might be run on equipment other than 
that for which the program is initially written.
--The graphics program is to be understood and maintained by 
programmers other than the original ones.
--The graphics program is or is likely to be used by organizations 
outside the Federal government (i.e., State and local governments, and 
others).

    9.3  Nonstandard features of implementations of PHIGS should be 
used only when the needed operation or function cannot reasonably be 
implemented with the standard features alone. Although nonstandard 
features can be very useful, it should be recognized that the use of 
these or any other nonstandard elements may make the interchange of 
graphics programs and future conversion more difficult and costly.
    10. Specifications. American National Standard Programmer's 
Hierarchical Interactive Graphics System, ANSI/ISO 9592.1-3:1989 and 
ANSI/ISO 9592.1a,2a,3a,4:1992, define the scope of the specifications, 
the syntax and semantics of the PHIGS elements and requirements for 
conforming implementations. All of these specifications apply to 
Federal Government implementations of this standard.
    ANSI/ISO 9592.1-3:1989 and ANSI/ISO 9592.1a,2a,3a,4:1992 define a 
language independent nucleus of a graphics system for integration into 
a programming language. Thus, it is embedded in a language layer 
obeying the particular conventions of the language. FIPS 153-1 is 
therefore divided into two parts. Part 1 represents the functional 
aspects of PHIGS. Part 1 consists of the following:
    (1) Functional description (ANSI/ISO 9592.1:1989) and (ANSI/ISO 
9592.1a:1992, Amendment 1)
    The functional description of PHIGS provides a set of functions for 
the definition, display and modification of 2D or 3D graphical data. It 
also provides for the definition, display and manipulation of 
geometrically related objects, along with the modification of graphics 
data and the relationships between that graphical data.
    (2) Archive file format (ANSI/ISO 9592.2:1989) and (ANSI/ISO 
9592.2a:1992, Amendment 1)
    The archive file provides a file format suitable for the storage 
and retrieval of PHIGS structures and structure network definitions. It 
allows structure definitions to be stored in an organized way on a 
graphical software system. And, facilitates transfer of structure 
definitions between different graphical software systems.
    (3) Clear-text encoding (ANSI/ISO 9592.3:1989) and (ANSI/ISO 
9592.3a:1992, Amendment 1)
    The clear-text encoding provides a representative of the archive 
file syntax that is easy to type, edit and read. The file is human-
readable (allows editing), human friendly (easy and natural to read) 
and machine readable (parsable by software).
    (4) Plus Lumiere and Surfaces, PHIGS PLUS (ANSI/ISO 9592.4:1992)
    The Programmer's Hierarchical Interactive Graphics System (PHIGS) 
Plus Lumiere and Surfaces (PHIGS PLUS) extends the basic PHIGS 
functionality by adding facilities for the specification of curved 
lines, curved and faceted surfaces, lighting and other effects such as 
depth modulation.
    Part 2 of FIPS 153-1 consists of the bindings of PHIGS and PHIGS 
PLUS functions to actual programming languages, defined in ANSI/ISO 
9593:1990. These bindings are developed in cooperation with the 
voluntary standards committees of the various languages. The following 
bindings currently exist, and form part 2 of FIPS 153-1:

--The FORTRAN Language binding for PHIGS (ANSI/ISO 9593.1:1990);
--The ADA Language binding for PHIGS (ANSI/ISO 9593.3:1990);
--The C Language binding for PHIGS (ANSI/ISO 9593.4:1991).

    Subsequent language bindings, including those for PHIGS PLUS, will 
be added periodically as they become available. As these bindings are 
approved by ANSI, each language binding will become part of this 
standard.
    11. Implementation. Implementation of this standard involves four 
areas of consideration: the effective date, acquisition of PHIGS 
software system implementations, interpretations of PHIGS 
implementations, and validation of PHIGS implementations.
    11.1  Effective Date. This revised standard is effective August 1, 
1995. Requirements for the use of basic PHIGS functionality (defined in 
ANSI/ISO 9592.1-3:1989 and ANSI/ISO 9593.1:1990, 9593.3:1990, 
9593.4:1991) are unchanged and continue in effect. Validation of PHIGS 
implementations is required after the effective date in accordance with 
Section 11.4.
    11.2  Acquisition of Implementations. Conformance to FIPS for PHIGS 
is required whether PHIGS toolbox packages are developed internally, 
acquired as part of an ADP system procurement, acquired by separate 
procurement, used under an ADP leasing arrangement, or specified for 
use in contracts for programming services. Recommended terminology for 
procurement of FIPS for PHIGS is contained in the U.S. General Services 
Administration publication Federal ADP & Telecommunications Standard 
Index, Chapter 4 Part 1.
    11.3  Interpretation of this FIPS. NIST provides for the resolution 
of questions regarding FIPS for PHIGS specifications and requirements, 
and issues official interpretations as needed. Procedures for 
interpretations are specified in FIPS PUB 29-3. All questions about the 
interpretation of FIPS for PHIGS should be addressed to: 
[[Page 5365]] Director, Computer Systems Laboratory (CSL), Attn: PHIGS 
Interpretation, National Institute of Standards and Technology, 
Gaithersburg, MD 20899, Telephone: (301) 975-3265.
    11.4  Validation of PHIGS Implementations. Implementations of FIPS 
for PHIGS using either FORTRAN or C bindings shall be validated in 
accordance with NIST Computer Systems Laboratory (CSL) validation 
procedures for FIPS for PHIGS. Recommended procurement terminology for 
validation of FIPS for PHIGS is contained in the U.S. General Services 
Administration publication Federal ADP & Telecommunications Standards 
Index, Chapter 4 Part 2. This GSA publication provides terminology for 
three validation options: Delayed Validation, Prior Validation Testing, 
and Prior Validation. The agency shall select the appropriate 
validation option. The agency is advised to refer to the NIST 
publication Validated Products List for information about the 
validation status of PHIGS products. This information may be used to 
specify validation time frames that are not unduly restrictive of 
competition.
    The agency shall specify the criteria used to determine whether a 
Validation Summary Report (VSR) or Certificate is applicable to the 
hardware/software environment of the PHIGS implementation offered. The 
criteria for applicability of a VSR or Certificate should be 
appropriate to the size and timing of the procurement. A large 
procurement may require that the offered version/release of the PHIGS 
implementation shall be validated in a specified hardware/software 
environment and that the validation shall be conducted with specified 
hardware/software features or parameter settings; e.g., the same 
parameter settings to be used in a performance benchmark. An agency 
with a single-license procurement may review the Validated Products 
List to determine the applicability of existing VSRs or Certificates to 
the agency's hardware/software environment.
    PHIGS implementations using either FORTRAN or C bindings shall be 
validated using the NIST PHIGS Test Suite, a suite of automated 
validation tests for PHIGS implementations. The NIST PHIGS Test Suite 
was first released in July 1990 to help users and vendors determine 
compliance with FIPS for PHIGS. The most recent version of the test 
suite will be used for validating conformance of PHIGS implementations 
after the effective date of FIPS PUB 153-1. The results of validation 
testing by the PHIGS Testing Service are published on a quarterly basis 
in the Validated Products List, available from the National Technical 
Information Service (NTIS). See related documents section.
    Each release of the test suite has provided additional language 
bindings and test cases to increase the test suite's coverage of PHIGS 
functionality. Version 2.1 of the NIST PHIGS Test Suite, released in 
April 1994, provides testing for PHIGS implementations using either the 
FORTRAN or C language binding. Version 2.1 does not include tests for 
the functionality of PHIGS PLUS added by this revision of FIPS of 
PHIGS.
    A PHIGS Test Suite license includes all of the tests described 
above, documentation, and automatic notifications of approved changes 
to the PHIGS Test Suite for a six month period. A license for the most 
recent version of the PHIGS Test Suite is a necessary requirement for 
an organization that desires to be tested by the NIST PHIGS Testing 
Service after the effective date of FIPS 153-1.
    Current information about the NIST PHIGS Validation Service and 
validation procedures for FIPS for PHIGS is available from: National 
Institute of Standards and Technology, Computer Systems Laboratory, 
Graphics Software Group, Building 225, Room A266, Gaithersburg, MD 
20899, (301) 975-3265.
    12. Waivers. Under certain exceptional circumstances, the heads of 
Federal departments and agencies may approve waivers to Federal 
Information Processing Standards (FIPS). The head of such agency may 
redelegate such authority only to a senior official designated pursuant 
to section 3506(b) of Title 44, United States Code.
    Waivers shall be granted only when:
    a. Compliance with a standard would adversely affect the 
accomplishment of the mission of an operator of a Federal computer 
system, or
    b. Cause a major adverse financial impact on the operator which is 
not offset by Governmentwide savings.
    Agency heads may act upon a written waiver request containing the 
information detailed above. Agency heads may also act without a written 
waiver request when they determine that conditions for meeting the 
standard cannot be met. Agency heads may approve waivers only by a 
written decision which explains the basis upon which the agency head 
made the required findings(s). A copy of each such decision, with 
procurement sensitive or classified portions clearly identifed, shall 
be sent to: National Institute of Standards and Technology; Attn: FIPS 
Waiver Decisions, Technology Building, Room B-154; Gaithersburg, MD 
20899. In addition notice of each waiver granted and each delegation of 
authority to approve waivers shall be sent promptly to the Committee on 
Government Operations of the House of Representatives and the Committee 
on Governmental Affairs of the Senate and shall be published promptly 
in the Federal Register.
    When the determination on a waiver applies to the procurement of 
equipment and/or services, a notice of the waiver determination must be 
published in the Commerce Business Daily as a part of the notice of 
solicitation for offers of an acquisition or, if the waiver 
determination is made after that notice is published, by amendment to 
such notice.
    A copy of the waiver, any supporting documents, the document 
approving the waiver and any supporting and accompanying documents, 
with such deletions as the agency is authorized and decides to make 
under 5 U.S.C. Sec. 552(b), shall be part of the procurement 
documentation and retained by the agency.
    13. Where to Obtain Copies. Copies of this publication are for sale 
by the National Technical Information Service, U.S. Department of 
Commerce, Springfield, VA 22161. (Sale of the included specifications 
document is by arrangement with the American National Standards 
Institute. When ordering, refer to Federal Information Processing 
Standards Publication 153-1 (FIPSPUB153-1) and title. Payment may be 
made by check, money order, or deposit account.

Appendix A--The Family of Graphics Standards

    The following computer graphics standards are now available to 
address the needs of government applications in creating, modifying, 
manipulating, and exchanging computer-generated pictures:
     FIPS PUB 120-1, the Graphical Kernel System (GKS), which 
adopts ANSI X3.124-1985;
     FIPS PUB 153-1, the Programmer's Hierarchical Interactive 
Graphics System (PHIGS), which adopts ANSI/ISO 9592-1989;
     FIPS PUB 128-1, the Computer Graphics Metafile (CGM), 
which adopts ANSI/ISO 8632-1992 and
     FIPS PUB 177, the Initial Graphics Exchange Specification 
(IGES), which adopts ASME/ANSI Y14.26M-1989.
    In addition, the Computer Graphics Interface (CGI) has recently 
become an International standard, and is expected to be issued as a 
FIPS. [[Page 5366]] 
    These standards fall into two categories: Application Programmer's 
Interface (API) standards, and Interoperability standards. The goal of 
API standards is to enhance the portability of graphics programs (and 
programmers) between installations and environments. The goal of 
Interoperability standards is to enable graphics data to be exchanged 
successfully between graphics systems and devices.
    Figure 1 is a very simple reference model of a computer graphics 
operating environment. The model emphasizes that a graphics application 
program interacts with physical devices and human operators via a 
computer graphics environment. Figure 1 also shows that the application 
may receive information from an external database.
    The output of the graphics program, as shown in Figure 1, is 
directed to a virtual graphics device (i.e., Virtual Device Interface 
or VDI) rather than directly to a physical device. A Device Driver 
provides an interface, implemented in either hardware or software, for 
translating virtual device commands to commands understood by a 
particular physical device. By substituting one device driver for 
another, an application can run on a different physical device. This 
device independence is a central concept of this graphics reference 
model.
    In Figure 1, the API standards reside in the box labelled the 
Device Independent Graphics Package. Interoperability standards are 
related to the boxes in Figure 1 labelled Metafile, Database and 
Virtual Device Interface. Figure 2 depicts the various graphics 
standards associated with the general model shown in Figure 1. These 
are discussed below.

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Application Programmer's Interface (API) Standards

    Standards at the API promote program and programmer portability. A 
standard at this level specifies a set of operations on a variety of 
graphics objects. An API standard provides for the portability of 
applications across a wide range of computer hardware, operating 
systems, programming languages, and graphics devices. A program written 
to an API standard at one facility in one environment should be easily 
transferable to another facility in a different environment. Facility 
dependencies should be the major area requiring modification.
    The specific functions supported by a particular API standard 
provide certain capabilities. The application programmer, by 
identifying the capabilities needed, determines the API better suited 
for the application. As shown in Figure 2, there are currently two 
graphics API standards, GKS and PHIGS.
    GKS provides a functional description of a two-dimensional (2D) 
graphics interface. It provides the basic graphics support required by 
a wide variety of application requiring the production of computer-
generated pictures. A procedural language binding of a functional 
standard specifies the exact name for each operation, its parameter 
sequence, and the data types for the parameters. FORTRAN, Pascal, Ada 
and C language bindings are parts of GKS.
    GKS is suitable for use in graphics programming applications that 
employ a broad spectrum of graphics, from simple passive graphics 
output (where pictures are produced solely by output functions without 
interaction with an operator) to interactive applications; and which 
control a whole range of graphics devices, including but not limited to 
vector and raster devices, microfilm recorders, storage displays, 
refresh displays, and color displays.
    PHIGS provides for the definition, display, modification, and 
manipulation of 2D and graphical data. It provides functionality to 
support storage of graphics and application data in a hierarchical 
form. Information may be inserted, changed, and deleted from the 
hierarchical data storage with the functions provided by PHIGS. 
Language binding specifications for PHIGS include FORTRAN, C and Ada.
    PHIGS is specifically designed to meet the performance requirements 
of such demanding applications as Computer Aided Design/Computer Aided 
Engineering/Computer Aided Manufacturing, command and control, 
molecular modelling, simulation and process control.
    Capabilities in PHIGS but not in GKS include: the centralized 
hierarchical data storage; the dynamic and responsive nature of 
interactions; the addition of a modeling capability; and support for 
color models other than Red-Green-Blue (RGB).

Interoperability Standards

    Graphics Interoperability standards allow graphical data to be 
interchanged between graphics devices. As shown in Figure 2, there are 
three graphics interoperability standards, CGM, (future) CGI, and IGES.
    CGM is used for the storage and transfer of picture description 
information. It enables pictures to be recorded for long term storage, 
and to be exchanged between graphics devices, systems, and 
installations. As indicated in Figure 2, the storage mechanism for CGM 
is in the form of a neutral file format called a metafile. The software 
which creates the metafile is known as a CGM Generator. The software 
which reads and displays a CGM metafile is known as an Interpreter.
    CGM specifies a semantic interface that describes 2D graphical 
entities using primitives (like polyline, text, and ellipse) and 
attributes (like color, line width, interior style, and fonts). CGM is 
compatible with the specification of 2D elements in GKS. A data 
encoding specifies the exact sequence of bits used to represent each 
operation and its parameters. CGM contains three types of data stream 
encodings (binary, character, and clear text) to provide the 
implementor choices depending on the particular application.
    IGES provides a method for representing and storing geometric, 
topological, and non-geometric product definition data that is 
independent of any one system. Where CGM transfers graphical pictures, 
IGES transfers a graphical database which can be processed to represent 
a picture. Thus IGES represents more than just purely graphical data. 
As Figure 2 indicates, the storage mechanism for IGES is in the form of 
a neutral format that must be translated by a Preprocessor and 
Postprocessor for conversion between systems. IGES permits the 
compatible exchange of product definition data used by various computer 
aided design/computer aided manufacturing (CAD/CAM) systems.
    The future CGI standard is designed to specify the exchange of 
information at the Virtual Device Interface. It will provide an 
interface between the device independent and device dependent parts of 
a graphic system. Since CGI contains information at a vitual level, it 
can be used to create a CGM. A CGM can also be output on a CGI device 
in a straightforward manner.

[FR Doc. 95-2103 Filed 1-26-95; 8:45 am]
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