HELPLIB.HLB  —  Ext File Specs, Overview
    Extended File Specifications includes support for the following:

    o  The ODS-5 disk structure. ODS-5 is an extension to the
       existing ODS-2 disk structure, and adds the ability to use
       extended file names that can be more easily mapped between
       Windows and OpenVMS. ODS-5 expands the available character
       set and filename length to be consistent with Windows 95 and
       Windows NT, and sets the stage for future Unicode file name
       support through PATHWORKS.

    o  Deeper directories. Enhancements to RMS provide deep directory
       support on both ODS-2 and ODS-5 volumes.

    Taken together, these components provide much greater flexibility
    for OpenVMS Alpha systems (using Advanced Server for OpenVMS
    7.2, formerly known as PATHWORKS for OpenVMS), to store, manage,
    serve, and access files that have names similar to those in a
    Windows 95 or Windows NT environment.

    This topic provides an overview of the benefits, features,
    and support for Extended File Specifications, as well as
    changes in OpenVMS behavior that occur when using Extended File
    Specifications.

1  –  Benefits

    The deep directories and extended file names supported by
    Extended File Specifications provide the following benefits:

    o  OpenVMS system managers can manage files with extended names
       and deep directories in the same manner as Windows NT users.

    o  Users of Advanced Server for OpenVMS 7.2 (formerly known as
       PATHWORKS for OpenVMS) have the ability to store longer file
       names and use deeper directory structures, which are more
       compatible with Windows 95 and Windows NT file names.

    o  Applications developers who are porting applications from
       other environments that have support for deep directories can
       use a parallel structure on OpenVMS.

    o  Longer file naming capabilities and Unicode support enables
       OpenVMS Alpha Version 7.2 and later to act as a DCOM server
       for Windows NT clients, and ODS-5 provides capabilites that
       make the OpenVMS and Windows NT environment more homogeneous
       for DCOM developers.

    o  JAVA applications on OpenVMS will comply with JAVA object
       naming standards.

    o  General OpenVMS users can make use of long file names, new
       character support, and the ability to have lowercase and
       mixed-case file names.

2  –  Features

    Extended File Specifications consists of two main features, the
    ODS-5 volume structure, and support for deep directories.

2.1  –  ODS-5

    OpenVMS Alpha Version 7.2 and later implements On-Disk Structure
    Level 5 (ODS-5). This structure provides the basis for creating
    and storing files with extended file names. You can choose
    whether or not to enable ODS-5 volumes on your OpenVMS Alpha
    systems.

    The ODS-5 volume structure allows the following features:

    o  Long file names

    o  More characters legal within file names

    o  Preservation of case within file names

2.2  –  Deep Directories

    Both ODS-2 and ODS-5 volume structures support deep nesting of
    directories, subject to the following limits:

    o  There can be up to 255 levels of directories.

    o  The name of each directory can be up to 236 8-bit or 117
       16-bit characters long.

    Complete file specifications longer than 255 bytes are
    abbreviated by RMS when presented to unmodified applications.

    For example, a user can create the following deeply nested
    directory:

    $ CREATE/DIRECTORY [.a.b.c.d.e.f.g.h.i.j.k.l.m]

    A user can create the following directory with a long name on an
    ODS-5 volume:

    $ CREATE/DIRECTORY
    [.AVeryLongDirectoryNameWhichHasNothingToDoWithAnythingInParticular]

2.2.1  –  Directory Naming Syntax

    On an ODS-5 volume, directory names conform to most of the same
    conventions as file names when using the ISO Latin-1 character
    set. Periods and special characters can be present in the
    directory name, but in some cases, they must be preceded by a
    circumflex (^) in order to be recognized as literal characters.

3  –  Considerations

    ODS-5 is being introduced primarily to provide enhanced file
    sharing capabilities for users of Advanced Server for OpenVMS 7.2
    (formerly known as PATHWORKS for OpenVMS), as well as DCOM and
    JAVA applications.

    System managers must understand the impact of an ODS-5
    environment before enabling it for general users. It is essential
    that system managers perform the following steps before enabling
    ODS-5:

    o  Review all ODS-5 restrictions.

    o  Understand the support levels for different OpenVMS
       applications.

    o  Segregate applications that do not support ODS-5 or have not
       been tested with ODS-5 names or volumes.

                                   NOTE

       It is recommended that you enable ODS-5 disks in a
       homogeneous OpenVMS Version 7.2 (and later) Alpha cluster
       only.

3.1  –  Mixed-Version Support

    Users on OpenVMS Alpha Version 7.2 (and later) systems can
    take advantage of Extended File Specifications capabilities. In
    contrast, systems running prior versions of OpenVMS cannot mount
    ODS-5 volumes, correctly handle extended file names, or even see
    extended file names.

    The following topics describe support on OpenVMS Version 7.2
    (and later) and on prior versions of OpenVMS in a mixed-version
    cluster.

    Users on OpenVMS Alpha Version 7.2 (and later) Systems

    Users on OpenVMS Alpha Version 7.2 and later systems can continue
    to access pre-Version 7.2 files and directories; for example,
    they can do all of the following:

    o  Create and access deep directory structures on ODS-2 volumes.

    o  Read a BACKUP saveset created on an earlier version of
       OpenVMS.

    o  Use DECnet to copy a file with an ODS-5 name to a file with an
       ODS-2 name on a system running an earlier version of OpenVMS.

    Users on pre-Version 7.2 Systems

    On mixed-version clusters, some restrictions exist. Users on a
    version of OpenVMS prior to Version 7.2:

    o  Cannot access any files on an ODS-5 volume. This is true
       regardless of whether the volume is connected physically on
       a CI or SCSI bus, or by an MSCP or QIO server.

    o  Cannot successfully create or restore an ODS-5 image saveset.
       However, these users can successfully restore ODS-2-compliant
       file names from an ODS-5 saveset.

3.2  –  Mixed-Architecture Support

    All Extended File Specifications capabilities are available on
    OpenVMS Alpha Version 7.2 and later systems. Current ODS-2 volume
    and file management functions remain the same on both VAX and
    Alpha Version 7.2 (and later) systems; however, extended file
    naming and parsing are not available on VAX systems.

    The following topics describe support on OpenVMS VAX and Alpha
    systems in a mixed-architecture cluster.

    Limited Extended File Specifications Capabilities on VAX Systems

    In mixed-architecture OpenVMS Version 7.2 (and later) clusters,
    the following Extended File Specifications capabilities are
    available on OpenVMS Version 7.2 (and later) VAX systems:

    o  Ability to mount an ODS-5 volume

    o  Ability to write and manage ODS-2-compliant files on an ODS-5
       volume

    o  See only \pISO_LATIN\.??? or \pUNICODE\.??? when accessing an
       ODS-5 file specification

    BACKUP Limitations

    In a mixed architecture cluster, users cannot successfully create
    or restore an ODS-5 image saveset. However, these users can
    successfully restore ODS-2-compliant file names from an ODS-5
    saveset.

3.3  –  Network Support

    Although Extended File Specifications is intended to provide
    enhanced file naming capabilities to Advanced Server for OpenVMS
    7.2 Version 7.2 for OpenVMS Version 7.2, network access with
    ODS-5 volumes and extended file names is currently being tested.
    The length of an extended file specification that can be passed
    over the network using DECnet is restricted to a maximum of 255
    bytes.

3.4  –  Application Support

    OpenVMS applications should be evaluated and tested to determine
    whether they function correctly when Extended File Specifications
    is enabled. The OpenVMS System Manager's Manual, Volume 1:
    Essentials contains guidelines for evaluating applications, and
    the Guide to OpenVMS File Applications contains details about the
    technical aspects of Extended File Specifications that can affect
    the behavior of an application.

3.5  –  User Support

    When you enable ODS-5 volumes on an OpenVMS cluster, you should
    make users aware of the following characteristics:

    o  Extended file names caooonot be used on ODS-2 volumes.

    o  Case is determined by the first instance of an extended file
       name.

    o  There are special rules for case preservation and case
       blindness when using extended file names.

    o  Some system utilities and DCL commands have a /STYLE qualifier
       to control the display of file names.

    o  Error messages can vary when different parse style are used.

    o  Extended file names are not visible from a VAX system.

    The OpenVMS System Manager's Manual, Volume 1: Essentials
    contains information for setting user's expectations of Extended
    File Specifications.

4  –  Impact

    The main goal of Extended File Specifications is to provide
    extended file naming capabilities, while also:

    o  Maintaining high reliability, scalability, and availability

    o  Maintaining the traditional (ODS-2) serial file interoperation
       capabilities

    o  Causing the least possible amount of change for layered
       products and applications

    However, once ODS-5 volumes are enabled, some of the new
    capabilities can potentially impact certain applications or
    layered products, as well as some areas of system management.

    The following guidelines and description of changes in the base
    operating system will help you determine the level of impact on
    your OpenVMS environment.

4.1  –  Support Guidelines

    Under Extended File Specifications, existing applications and
    layered products that are coded to documented interfaces, as well
    as most DCL command procedures, should continue to work without
    modification.

    However, applications that are coded to undocumented interfaces,
    or include any of the following, may need to be modified in order
    to function as expected on an ODS-5 volume:

    o  Internal knowledge of the file system, including knowledge
       of:

          The data layout on disk
          The contents of file headers
          The contents of directory files

    o  File parsing tailored to a particular on-disk structure.

    o  Assumptions about the syntax of file specifications, such as
       the placement of delimiters and legal characters.

    o  Assumptions about the case of file specifications. Mixed
       and lowercase file specifications will not be converted to
       uppercase, which can affect string matching operations.

    o  Assumptions that file specifications are identical between RMS
       and the file system.

                                   NOTE

       All unmodified XQP applications running on an OpenVMS
       VAX or Alpha system that access an ODS-5 volume will see
       pseudonames returned in place of Unicode or ISO Latin-
       1 names that are not ODS-2 compliant. This can cause
       applications to act in an unpredictable manner.

       Applications that specify or retrieve filenames with the
       XQP interface using ODS-5 disks must be modified in order to
       access files with extended names.

4.2  –  RMS Changes

    To support Extended File Specifications, the Record Management
    Services (RMS) have been enhanced to provide the following
    functions through existing interfaces:

    o  Support for a wider range of characters in a file name,
       extension, and directory

    o  Access to file specifications with extended characters

    o  Support for directory structures deeper than eight levels

    o  Access to file specifications longer than 255 bytes through
       the NAM block with some restrictions in functionality

    o  Access and complete specification of file specifications
       longer than 255 bytes by callers who are aware of the new
       naming characteristics through a new interface (NAML block)

4.2.1  –  Extended File Names

    With ODS-5 enabled, RMS can manipulate filenames and subdirectory
    specifications of up to 255 8-bit or 16-bit characters in length.
    RMS can handle a total path name 512 8-bit or 16-bit characters
    in length.

    Prior to OpenVMS Alpha Version 7.2, the NAM block interface could
    pass file specifications of up to 255 bytes each (including the
    resultant file specification). The following topics describe the
    changes that allow for passing longer file specifications and
    that provide compatibility with applications using the NAM block
    interface prior to this release.

4.2.2  –  Additional Character Sets

    With ODS-5, RMS supports access to files and directories whose
    names contain arbitrary 8-bit characters, except for the C0
    control set (hex 00 through 1F) and the following characters:

       Double quotation marks (")
       Asterisk (*)
       Backslash (\)
       Colon (:)
       Left and right angle brackets (< >)
       Slash (/)
       Question mark (?)
       Vertical bar (|)

    Note that this explicitly includes both the C1 character set (hex
    80-9F) as well as graphical and other characters between 9F and
    FF. This allows the entire ISO Latin-1 character set (with the
    7-bit character exclusions noted above) and any defined Unicode
    character.

4.2.3  –  Deeply Nested Directories

    Under Extended File Specifications on Alpha, RMS supports deep
    nesting of up to 255 directories, with the restriction that the
    total directory specification must be no longer than 512 8-bit
    or 16-bit characters. The deep nesting of directories is also
    supported on ODS-2 disks.

4.3  –  File System (XQP) Changes

    The following Files-11 Extended QIO Processor (XQP) file system
    enhancements are offered under Extended File Specifications
    through the $QIO interface. Note that in some cases, XQP file
    format rules may differ from those that apply to other system
    services that accept file names, such as those provided by RMS.

    o  The current restrictions on the format and content of file
       names have been modified, specifically:

       -  The 39.39 file name length restriction was removed to allow
          longer file names, up to 236 8-bit characters or 117 16-bit
          characters

       -  The use of characters from the ISO Latin-1 multinational
          character set is supported in file specifications

       -  Support for the entry and storage of file and directory
          specifications in Unicode.

4.4  –  DCL Commands and Utilities

    In DCL commands, you can select either of the following styles
    for parsing file specifications:

    o  Traditional filenames are allowed on both ODS-2 and ODS-5
       volumes.

    o  Extended filenames are allowed on ODS-5 but not on ODS-2
       volumes.

    Some OpenVMS commands and utilities have new qualifiers to
    control the interpretation and display of file specifications.

                                   NOTE

       DCL lexical functions use the DEC-Multinational character
       set, which is different from the ISOLatin-1 character set
       used for file names on an ODS-5 disk. This can lead to
       unexpected results if, for example, you use the DCL function
       F$EDIT to upcase a filename.

    Some DCL commands and OpenVMS utilities have been specifically
    modified to take advantage of all the features of extended file
    names. These utilities and commands accept and handle extended
    file specifications without error and without modifying their
    expected case.

    Other DCL commands and OpenVMS utilities have had little or
    no modification to take advantage of extended file names.
    These utilities and commands are expected to handle most of
    the attributes of extended file specifications (such as new
    characters and deep directory structures) correctly.

    Extended File Specifications Support fully defines the different
    levels of support for extended file names provided by DCL
    commands and OpenVMS utilities in OpenVMS Version 7.2 and later.

    The following DCL commands and OpenVMS utilities provide full
    support for extended file names:

       ANALYZE /AUDIT
       ANALYZE /DISK
       ANALYZE /RMS
       BACKUP
       CONVERT
       CONVERT /RECLAIM
       COPY
       CREATE /DIRECTORY
       DELETE
       DIRECTORY
       DUMP
       EDIT /ACL
       EXCHANGE /NETWORK
       FDL
       PURGE
       RECOVER/RMS
       RENAME
       SEARCH
       SET SECURITY
       SYSMAN
       TYPE

 The following table lists the new features in DCL to support
 Extended File Specifications.

    DCL Command            New Features

    COPY                   Added new qualifier, /STYLE, with new
                           keywords, EXPANDED and CONDENSED
    DELETE                 Added new qualifier, /STYLE, with new
                           keywords, EXPANDED and CONDENSED
    DIRECTORY              Added the following items:

                           o  Qualifier, /STYLE, with new keywords,
                              EXPANDED and CONDENSED

                           o  Display item to /FULL to display Client
                              Attributes

    DUMP                   Added the following items:

                           o  Display item to /DIRECTORY to display
                              Name type attribute

                           o  Display item to /HEADER to display new
                              attributes

                           o  Qualifier, /STYLE, with new keywords,
                              EXPANDED and CONDENSED

    EXCHANGE NETWORK       Added new qualifier, /STYLE, with new
                           keywords, EXPANDED and CONDENSED
    F$FILE_ATTRIBUTES      Added new item codes: FILE_LENGTH_HINT,
    Lexical                VERLIMIT, DIRECTORY
    F$GETDVI Lexical       Added new type to the ACPTYPE item code.
    F$GETJPI Lexical       Added new item codes: PARSE_STYLE_PERM and
                           PARSE_STYLE_IMAGE
    INITIALIZE             Added a new qualifier: /STRUCTURE=5
                           device-name[:] volume-label
    PRINT                  Added new qualifier, /STYLE, with new
                           keywords, EXPANDED and CONDENSED
    PURGE                  Added new qualifier, /STYLE, with new
                           keywords, EXPANDED and CONDENSED
    RENAME                 Added new qualifier, /STYLE, with new
                           keywords, EXPANDED and CONDENSED
    SEARCH                 Added new qualifier, /STYLE, with new
                           keywords, EXPANDED and CONDENSED
    SET ACL                Added new qualifier, /STYLE, with new
                           keywords, EXPANDED and CONDENSED
    SET DEFAULT            Updated the following items:

                           o  Modified the directory-spec parameter
                              to accept ODS-5-compliant file
                              specifications.

    SET DIRECTORY          Added new qualifier, /STYLE, with new
                           keywords, EXPANDED and CONDENSED
    SET FILE               Added new qualifier, /STYLE, with new
                           keywords, EXPANDED and CONDENSED
    SET PROCESS            Added a new qualifier: /PARSE_
                           STYLE=(keyword), where keywords are
                           TRADITIONAL and EXTENDED.
    SET SECURITY           Added new qualifier, /STYLE, with new
                           keywords, EXPANDED and CONDENSED
    SET VOLUME             Added a new qualifier: /STRUCTURE_LEVEL=5
    SHOW DEVICE/FULL       Updated the display information to show
                           the disk structure level.
    SUBMIT                 Added new qualifier, /STYLE, with new
                           keywords, EXPANDED and CONDENSED
    TYPE                   Added new qualifier, /STYLE, with new
                           keywords, EXPANDED and CONDENSED

    For detailed information about the enhancements made to the
    OpenVMS operating system and utilities in support of Extended
    File Specifications, see the OpenVMS DCL Dictionary: A-M, the
    OpenVMS DCL Dictionary: N-Z, and the OpenVMS Utility Routines
    Manual.

4.5  –  DCL Command Parameters

    Command procedures that use file names as parameters can produce
    different results in an ODS-5 environment.

    See DCL Command Parameters for more information about using ODS-5
    style names in DCL command procedures.

4.6  –  System Services Changes

    The following system services have been modified or added to
    support Extended File Specifications:

    o  New services:

       -  $SET_PROCESS_PROPERTIESW

       -  $CVT_FILENAME

    o  Changed services:

       -  $CREPRC

       -  $GETJPI

       -  $SETDDIR
Close Help