Extended File Specifications is a feature of OpenVMS Alpha that
allows the use of Windows-style file specifications.
1 – 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.
1.1 – 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.
1.2 – Features
Extended File Specifications consists of two main features, the
ODS-5 volume structure, and support for deep directories.
1.2.1 – 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
1.2.2 – 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]
1.2.2.1 – 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.
1.3 – 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.
1.3.1 – 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.
1.3.2 – 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.
1.3.3 – 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.
1.3.4 – 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.
1.3.5 – 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.
1.4 – 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.
1.4.1 – 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.
1.4.2 – 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)
1.4.2.1 – 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.
1.4.2.2 – 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.
1.4.2.3 – 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.
1.4.3 – File System (XQP) Changes
The following Files-11 Extended QIO Processor (XQP) file system
enhancements are offered under Extended File Specifications
through the $QIO interface. Note that in some cases, XQP file
format rules may differ from those that apply to other system
services that accept file names, such as those provided by RMS.
o The current restrictions on the format and content of file
names have been modified, specifically:
- The 39.39 file name length restriction was removed to allow
longer file names, up to 236 8-bit characters or 117 16-bit
characters
- The use of characters from the ISO Latin-1 multinational
character set is supported in file specifications
- Support for the entry and storage of file and directory
specifications in Unicode.
1.4.4 – DCL Commands and Utilities
In DCL commands, you can select either of the following styles
for parsing file specifications:
o Traditional filenames are allowed on both ODS-2 and ODS-5
volumes.
o Extended filenames are allowed on ODS-5 but not on ODS-2
volumes.
Some OpenVMS commands and utilities have new qualifiers to
control the interpretation and display of file specifications.
NOTE
DCL lexical functions use the DEC-Multinational character
set, which is different from the ISOLatin-1 character set
used for file names on an ODS-5 disk. This can lead to
unexpected results if, for example, you use the DCL function
F$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.
1.4.5 – 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.
1.4.6 – 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
2 – Managing
Managing an OpenVMS system that implements Extended File
Specifications requires an understanding of the support provided
for different OpenVMS applications, how to enable and control
the new features, and the changes to OpenVMS system management
utilities. This topic contains the following subtopics:
o Levels of support provided by the current set of OpenVMS
commands and utilities that support Extended File
Specifications
o How to enable Extended File Specifications features on an
OpenVMS Alpha system
o How to control user access to ODS-5 features
o Changes to system management utilities
2.1 – Extended File Specifications Support
To help determine the expected behavior of OpenVMS utilities
and commands for ODS-5, the following levels of support have
been established. Each level outlines the acceptable behavior
of a utility or command when it encounters an extended (ODS-5
compliant) file specification.
The levels of support for ODS-5 are defined in the following
sections:
2.1.1 – Full Support
OpenVMS utilities and commands that offer full support for ODS-5
have been specifically modified to take advantage of all the
features of extended file naming. These utilities and commands
should accept and handle extended file specifications without
error and without modifying their expected case.
In addition, OpenVMS commands and utilities that fully support
Extended File Specifications can accept and produce long file
specifications that exceed the traditional 255-byte limit in
their original form-without requiring them to be abbreviated in
Directory ID (DID) or File ID (FID) format.
2.1.2 – Default Support
OpenVMS utilities and commands with default support have had
little or no modification to take advantage of Extended File
Specifications features. 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. However, issues with case sensitivity
and case blindness (such as converting lowercase characters to
uppercase) may occur.
In contrast with utilities that have full support, utilities with
default support rely on DID and FID abbreviation offered by RMS
to handle long file specifications. As a result, these utilities
are subject to the following restrictions related to DID and FID
abbreviation:
o Matching operations in an environment where FID abbreviation
is used may not always work as expected. For example, wildcard
matching operations may not capture all target file names
because the long file names may be represented in their
numeric FID abbreviation form. This restriction specifically
applies to matching operations that are performed outside of
RMS.
o Wildcards and sticky defaults cannot be used with a FID
abbreviation. For example, the following commands are illegal:
$ DIRECTORY a[1,2,3]*.txt
$ COPY a[1,2,3].txt *.txt2
Because FID abbreviations are a unique numeric representation
of one file, they cannot be used to represent or match any
other file.
o Creating a file using a FID abbreviation is illegal.
2.1.3 – No Support for Extended File Naming
OpenVMS utilities and commands that do not support extended
file naming can function on ODS-5 volumes; however, they are
restricted to operating with traditional file specifications
only. These utilities and commands should be used carefully
under Extended File Specifications because they may not function
successfully when they encounter extended file specifications.
2.1.4 – No Support for ODS-5
OpenVMS utilities and commands that do not support the ODS-
5 volume structure cannot handle extended file naming. These
utilities and commands should be used carefully under Extended
File Specifications because they may not function successfully
on ODS-5 volumes even when they only encounter traditional file
specifications.
The following table lists the OpenVMS utilities and commands
that do not support Extended File Specifications because of
limitations with either handling extended file names or the ODS-5
volume structure.
Component Notes
No ODS-5 Support
Disk defragmenters Unsupported unless a specific
defragmentation tool documents that it has
been updated to support an ODS-5 volume.
No Extended File Naming Support
Code compilers Cannot use extended file names for object
files. However, code compilers can create
applications that support extended names.
INSTALL
Known images Do not rename to an extended file name.
LINK Cannot output an image with an extended
file name.
Network files Do not rename to an extended file name.
(NET*.DAT)
Object modules (.OBJ) Do not rename to an extended file name.
Page and swap files Do not use an extended file name.
SYSGEN Do not write a parameter file with an
extended file name.
System startup files Do not rename to an extended file name.
3 – Using
Extended file names provide a wider variety of character set
options and naming conventions, similar to those available on
Windows NT. This topic describes the impact of Extended File
Specifications on the general user, and contains the following
subtopics:
o Differences in file and directory specifications between ODS-2
and ODS-5
o Manipulating extended file names
o Using extended file names in DCL command procedures
o Displaying ODS-5 file specifications in DECwindows
3.1 – File Specification Differences
With extended file names, there are two possible naming styles
for file specifications: traditional (ODS-2 compliant) and
extended (ODS-5 compliant). The following topics describe these
naming styles.
See also the OpenVMS User's Manual and the Guide to OpenVMS File
Applications for more information about file specifications in
Extended File Specifications.
3.1.1 – ODS-2 Syntax
The traditional (ODS-2) file name syntax is the syntax most
OpenVMS users have been accustomed to up to the advent of
extended file names. OpenVMS Versions 7.1 and earlier follow this
syntax, which supports the following character set and naming
conventions.
ODS-2 Character Set
The ODS-2 character set consists of alphanumeric characters (A-Z,
a-z, 0-9), dollar sign ($), underscore (_) and hyphen (-). The
hyphen (-) should not be used as the first or last character in a
file name. While it is possible to do this under some conditions,
special handling is required to access such a file once created.
Case Insensitivity
Case preservation is not supported with traditional syntax.
Commands may be entered in uppercase, lowercase, or mixed case;
however, all characters are stored in uppercase format.
Standard Delimiters
With traditional syntax, the file type is preceded by a period
(.). The file version is separated from the type by a semicolon
(;) or sometimes a period (.). (When the system displays file
specifications, it displays a semicolon in front of the file
version number.) Directories are enclosed by brackets ([]) or
angle brackets (<>). Directory levels are separated by periods
(.).
Limited File Length
Traditional file names follow the 39.39 format, supporting only a
single period (.) separating the name and type components.
3.1.2 – ODS-5 Syntax
The extended (ODS-5) file name syntax offered by Extended File
Specifications supports a larger character set and relaxes
restrictions on lengths of file names and use of characters. This
syntax allows Windows NT-style file names that use the following
character set and naming conventions to be stored on and accessed
by OpenVMS systems.
3.1.2.1 – Character Set Support
The ISO Latin-1 Multinational character set is a superset
of the traditional ASCII character set used by versions of
OpenVMS previous to 7.2. With extended file specifications, all
characters from the 8-bit ISO Latin-1 Multinational character set
are valid in file specifications, except the following:
C0 control codes (0x00 to 0x1F inclusive)
Double quotation marks (")
Asterisk (*)
Backslash (\)
Colon (:)
Left angle bracket (<)
Right angle bracket (>)
Slash (/)
Question mark (?)
Vertical bar (|)
File specifications on an ODS-5 volume can also include Unicode
(UCS-2) characters. Because each Unicode character requires
two bytes, the use of Unicode characters can affect the maximum
permitted lengths of file specifications.
3.1.2.2 – Special Characters
Some ISO Latin-1 characters require the circumflex (^) to precede
them in a file specification in order to be interpreted as
literal characters rather than special function characters.
The circumflex (^) is interpreted by the system as an escape
character.
o The circumflex (^) followed by underscore (_) or by a space
represents a space.
o The circumflex (^) followed by any of the following characters
means that the character is to be used as part of a file name
rather than having any special meaning that it might otherwise
have in a file specification:
. , ; [ ] % ^ &
o A user can enter a literal period (.) with or without the
circumflex (^) in a file name. The system adds the circumflex
to any periods other than those that act as delimiters for the
file type and version number. Literal periods (.) in directory
names must be preceded by the circumflex.
File names containing special characters cannot be accessed
from a VAX system.
3.1.2.3 – Interpretation of Period
The introduction of the period (.) as a literal character in
extended file names requires RMS to determine which periods are
file name characters and which are delimiters.
When only one period (.) is used in an extended file name, that
period is interpreted as the delimiter, as in "Venice.Venezia;1"
above. As in previous versions of OpenVMS, this behavior also
occurs if the single period is followed by a number:
$ CREATE Test.1
creates the file:
Test.1;1
When there are multiple periods (.) in a file name, the system
looks at all the characters after the last period. If those
characters are five or fewer digits, or a minus sign (-) followed
by five or fewer digits, the period is interpreted as a version
delimiter and the period previous to it is a type delimiter.
Notice that a legal version is less than or equal to 32767.
If you try to create the file "grandioso.x.33333", the "33333"
causes an illegal version error. If there is a nonnumeric
character following the last period then it is interpreted as
a type delimiter.
For example, the following command: $ CREATE Test4.3.2.1
creates the file: Test4^.3.2;1
where .2 is the file type and 1 is the file version.
3.1.3 – Expanded File Specification Length
On an ODS-5 volume, the file name together with the file type
can be up to 236 8-bit characters of 117 16-bit characters in
length. Unmodified programs and utilities may limit or abbreviate
complete file specifications to 255 bytes.
$ CREATE This.File.Name.Has.A.Lot.Of.Periods.DAT
$ CREATE -
_$ ThisIsAVeryLongFileName^&ItWillKeepGoingForLotsAndLotsOfCha -
_$ racters.ExceedingThe39^,39presentInPreviousVersionsOfOpenVMS
$ DIRECTORY
Directory TEST$ODS5:[TESTING]
ThisIsAVeryLongFileName^&ItWillKeepGoingForLotsAndLotsOfCharac
ters.ExceedingThe39^,39presentInPreviousVersionsOfOpenVMS;1
This^.File^.Name^.Has^.A^.Lot^.Of^.Periods.DAT;1
Total of 2 files.
3.1.4 – Case Preservation
Mixed-case and lowercase file names are retained in their
original form on ODS-5 volumes. However, the file system on
OpenVMS preserves the case of file names as they are first
entered. When you create more than one file with the same name
differing only in case, DCL treats the subsequent files as
versions, and converts them to the same case as the original
file.
For example, the following commands:
$ CREATE CaPri.;1
$ CREATE CAPRI
$ CREATE capri
produce the resulting files:
CaPri.;1 CaPri.;2 CaPri.;3
3.1.5 – Using Wildcards
Single- and multiple-character wildcards still function as
expected with ODS-5 files. A single-character wildcard represents
exactly one character in either the file name or file type, but
may not be used in the file version string. A multiple-character
wildcard can represent any number of characters starting with
zero in the file name or file type. A multiple-character wildcard
can be used in place of a version string.
3.1.5.1 – Wildcard Characters
The following characters are wildcard characters when working on
any OpenVMS 7.2 or later volume:
o The asterisk (*) is a multiple-character wildcard.
o The percent sign (%) is a single-character wildcard.
o The question mark (?) is a single-character wildcard.
The percent sign (%) continues to be a single-character wildcard
to maintain compatibility with existing applications. The percent
sign (%) may be used as a literal character when preceded by
the circumflex (^) and is also a literal character in Windows NT
file names. Therefore, in addition to the percent sign, RMS also
recognizes the question mark (?) as a single character wildcard.
The question mark functions identically to the percent sign as
a wildcard character on OpenVMS 7.2 and later. The percent sign
and the question mark matches exactly one character in a search
pattern.
3.1.5.2 – Wildcard Syntax
Although DCL preserves the case of extended file names, wildcard
matching is case blind.
When you perform a search operation with wildcards it continues
to match only against the corresponding character in the same
part of the target specification. The following table contains
examples of some wildcard searches.
The
pattern... matches... ...but doesn't match
A*B;* AHAB.;1 A.B;1
A.*.B* A^.DISK.BLOCK;1 A^.C^.B.DAT;1
A?B.TXT;* A^.B.TXT;5 A^.^.B.TXT;1
*.DAT Lots^.of^.Periods.dat;1DAT.;1
Mil?no.dat Milano.dat;1 Millaano.dat;1
NAPOLI.?.DAT napoli.q.dat;1 napoli.abc77.dat;1
3.1.6 – Case Sensitivity and Blindness
In prior versions of OpenVMS, DCL and RMS converted all
file specifications to uppercase. When using Extended File
Specifications, the case of all file names is preserved as
created by the user.
Files and directories can have mixed case names in extended file
names.
Original
file name ODS-2 Volume ODS-5 Volume
MILANO;1 MILANO.;1 MILANO.;1
SanRemo SANREMO.;1 SanRemo.;1
genoa..1 GENOA.;1 genoa.;1
3.2 – Directory Specification Differences
The following topics describe the deeper directory structures and
extended naming syntax available with Extended File Specifications.
It is now possible to go beyond the eight levels of directories
previously supported in OpenVMS.
See also the OpenVMS User's Manual and the Guide to OpenVMS File
Applications for more information about directory specifications
in Extended File Specifications.
3.2.1 – Deep Directory Structures
OpenVMS 7.2 and later 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.
For example, a user can create the following directories on an
ODS-2 or ODS-5 volume:
$ 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]
3.2.2 – Directory Naming Syntax
When using Extended File Specifications, directory names conform
to most of the same conventions as file names when using the
ISO Latin-1 character set. Periods and special characters may
be present in the directory name, but they must be preceded by a
circumflex (^) in order to be recognized as literal characters,
as shown in the following table:
CREATE/DIRECTORY. . . Result
[Hi^&Bye] Hi^&Bye.DIR;1
[Lots^.Of^.Periods^.In^.ThisLots^.Of^.Periods^.In^.This^
.Name.DIR;1
3.2.3 – Directory ID and File ID Abbreviation
Under some circumstances, a full file specification may contain
more characters than the 255 bytes allowed by unmodified
applications. If a file specification that such an application
needs exceeds 255 bytes in length, RMS generates a shorter
file specification by abbreviating the directory to a DID
abbreviation, and if necessary, the filename to a FID
abbreviation.
When the file specification is too long, RMS first attempts to
generate a shorter directory specification by identifying the
directory with its directory ID. This shorter specification is
referred to as a DID abbreviation.
TEST$ODS5:[5953,9,0]Alghero.TXT;1
Note that this form of the directory name must have three numbers
and two commas to avoid ambiguity with UIC format directory
names. With the DIRECTORY command you can view the shorter
DID abbreviation version as well as the full version of a file
specification.
3.3 – Working in Mixed Environments
If working in an environment which contains both OpenVMS Alpha
and OpenVMS VAX systems, it becomes more important to know on
which type of volume files are being created and on which type of
volume your default directory resides.
When accessing an ODS-5 volume, you need to set the parse style
to EXTENDED to accept and display extended file specifications.
The default setting is TRADITIONAL. To set the parse style, enter
the command:
$ SET PROCESS/PARSE_STYLE=EXTENDED
When working in a mixed environment of OpenVMS VAX and OpenVMS
Alpha, it is important for users to realize upon which system
they are working. OpenVMS 7.2 and later allows VAX systems to
mount ODS-5 volumes; however users on OpenVMS VAX systems can
access only files with ODS-2-compliant file names.
When working in a mixed environment of ODS-2 and ODS-5 volumes,
keep in mind the restrictions of ODS-2 file names when creating
files on ODS-5 volumes. If a file is created with special
characters on an ODS-5 volume, the file must be given an ODS-2
compliant name if it is copied to an ODS-2 volume.
3.4 – DCL Command Parameters
Command procedures that use file names as parameters can produce
different results in an ODS-5 environment.
You can switch from the TRADITIONAL to the EXTENDED parse style,
and this section describes the following areas that may be
affected if you choose to do so:
o Command procedure file specification
o Case preservation and $FILE
o Ampersand versus apostrophe substitution
3.5 – Command File Specification
If indirect command procedures are used, you may need to put
quotes around file specifications.
The following examples show the differences in output between
TRADITIONAL and EXTENDED parse styles when using the same command
file, SS.COM:
$ create ss.com
$ if p1 .nes. "" then write sys$output "p1 = ",p1
$ if p2 .nes. "" then write sys$output "p2 = ",p2
$ if p3 .nes. "" then write sys$output "p3 = ",p3
o Setting the parse style to an ODS-2 environment and running
SS.COM, the following output occurs:
$ set process/parse_style=traditional
$ @ss ^ p2 p3
p1 = ^
p2 = P2
p3 = P3
Note that the circumflex (^) is the first argument, and that
the case is not preserved for the p2 and p3 variables.
o Setting the parse style to an ODS-5 environment, the following
output occurs when running the same command procedure:
$ set process/parse_style=extended
$ @ss ^ p2 p3
p1 = ^ P2
p2 = P3
Note that the command procedure recognizes the circumflex (^)
as the escape character, and "^ P2" is the first argument.
o Adding quotes to the circumflex (^) produces the following
outcome:
$ @ss "^" p2 p3
p1 = ^
p2 = P2
p3 = P3
Because the circumflex (^) is within a quoted string, it is
not treated as an escape character.
o Adding quotes to the p3 variable produces the following
outcome:
$ @ss "^" p2 "p3"
p1 = ^
p2 = P2
p3 = p3
Note that the case is preserved for the p3 variable.
o In an ODS-2 environment, the following command treats the
circumflex (^) and the p2 and p3 strings as arguments, and the
command procedure produces the following results:
$ set process/parse_style=traditional
$ @ss^ p2 p3
p1 = ^
p2 = P2
p3 = P3
o In an ODS-5 environment, the circumflex (^) is treated as
the escape character and DCL looks for the file "SS^_P2.COM",
which results in the following error:
$ set process/parse_style=extended
$ @ss^ p2 p3
%DCL-E-OPENIN, error opening USER$DISK:[TEST]SS^_P2.COM; as input
-RMS-E-ACC, ACP file access failed
-SYSTEM-W-BADFILENAME, bad file name syntax
3.5.1 – Case Preservation and $FILE
DCL attempts to preserve the casing of file specifications. It
can do this only for commands defined with the Command Definition
Utility (CDU). DCL preserves case for any item defined in the
command definition file (.CLD) with the $FILE parse type.
Refer to the Command Definition Utility manual for more
information.
3.5.2 – Ampersand Versus Apostrophe Substitution
You can use ampersand (&) substitution as opposed to apostrophe
substitution, to preserve case during traditional parsing.
The following traditional parsing example shows a series of
commands that change the case of a character string:
$ set process/parse_style=traditional
$ x = "string"
$ define y 'x'
$ sho log y
"Y" = "STRING" (LNM$PROCESS_TABLE)
$ define y &x
%DCL-I-SUPERSEDE, previous value of Y has been superseded
$ sho log y
"Y" = "string" (LNM$PROCESS_TABLE)
Note that the use of the ampersand (&) preserved the case of the
character string assigned to the x variable.
Apostrophe substitution takes place before the command line is
set to uppercase, and ampersand substitution takes place after
the command line is set to uppercase.
The following extended parsing example shows the same series of
commands:
$ set process/parse_style=extended
$ define y 'x'
%DCL-I-SUPERSEDE, previous value of Y has been superseded
$ sho log y
"Y" = "string" (LNM$PROCESS_TABLE)
$ define y &x
%DCL-I-SUPERSEDE, previous value of Y has been superseded
$ sho log y
"Y" = "string" (LNM$PROCESS_TABLE)
Note that both character strings for the y variable are returned
lowercase. This happens because the DEFINE command uses $FILE,
which preserves the case.
Ampersand substitution can therefore be used to specify EXTENDED
file names even though the parse style is set to TRADITIONAL, as
shown in the following example:
$ set process/parse=extended
$ cre file^ name.doc
Contents of an ODS5 file
Exit
$ set process/parse=traditional
$ a = "file^ name.doc"
$ type file^ name.doc
%DCL-W-PARMDEL, invalid parameter delimiter - check use of special
characters
\^NAME\
$ type 'a'
%DCL-W-PARMDEL, invalid parameter delimiter - check use of special
characters
\^NAME\
$ type &a
Contents of an ODS5 file
NOTE
Ampersand substitution does not work for foreign commands.
3.6 – DECwindows Output
When using a DECwindows DECterm terminal emulator, you must
select UPSS ISO Latin-1 from the General... submenu on the
Options menu to display the full ISO Latin-1 character set
correctly.
F$EDIT assumes that the setting is 8-Bit Multinational
Characters, as do many text editors. This can affect the output
of ODS-5-compliant file specifications.
4 – Programming
The following topics describe how to evaluate an application's
support for Extended File Specifications, and provides guidelines
for upgrading that support.
4.1 – Evaluating Support Status
As part of testing OpenVMS Alpha Version 7.2 (and later),
OpenVMS application developers should evaluate and test all
existing applications to determine their current level of support
for Extended File Specifications and whether that level is
appropriate.
Most unmodified OpenVMS applications fall into the default
support category. Specifically, these applications use the
traditional NAM block rather than the new NAML block when making
RMS calls. Applications that use high-level language calls
to perform file operations will also fit into this category
unless the language run-time libraries have been modified to
full support. In most cases, you will not need to modify these
applications for them to function successfully under Extended
File Specifications. However, you can choose to upgrade these
applications to full support, if necessary.
However, any applications that are coded to undocumented
interfaces, or include any of the following may fall into one
of the no support categories:
1. Use of the QIO interface to specify file names. Developers
should examine all layered products and applications and
evaluate any file name interaction between the RMS and the
XQP interfaces. The format for extended file names varies for
each interface. As a result, valid file names could differ
between interfaces. (No extended file name support)
NOTE
All XQP applications that receive file names from the XQP
and encounter extended file names on a ODS-5 disk will
see pseudonames returned in place of Unicode (UCS-2) or
ISO Latin-1 names that are not ODS-2 compliant. This may
cause applications to act in an unpredictable manner.
2. Assumptions about the syntax of file specifications, such as
the placement of delimiters and legal characters. (No extended
file name support)
3. Assumptions about the case of file specifications. Mixed
and lowercase file specifications will not be converted to
uppercase, which could affect string matching operations. (No
extended file name support)
4. Dependence on the traditional directory depth (fewer than 8
levels). (No extended file name support)
5. Internal knowledge of the file system, which includes
knowledge of the contents of a directory and how file header
data is structured on a disk. (No ODS-5 support)
You can choose either to modify these applications to support
Extended File Specifications or not to use them under Extended
File Specifications.
4.2 – Upgrading Support
The following topics describe the changes necessary to upgrade
the level of support for ODS-5. Note that you must first ensure
that the application meets the default support level before you
can upgrade it to the full support level.
NOTE
If you are not using the RMS or QIO interfaces to perform
disk I/O, the Extended File Specifications support level of
your application depends on whether the interface you are
using (such as a language run-time library) provides full
support.
4.2.1 – Upgrading to Default Support
To upgrade an application to provide default support for Extended
File Specifications, you must ensure that it minimally supports
both the ODS-5 volume structure and extended file naming as
recommended in the following topics
4.2.2 – Supporting ODS-5
Applications that do not support the new ODS-5 volume
structure do not operate successfully on these volumes even
if they encounter only traditional file specifications.
These applications use physical or logical I/O to bypass the
file system when they access the volume or access directory
files or other metadata files directly, and therefore must be
installed with privileges or run by a user who has privileges.
These applications are usually system programs, such as disk
defragmenters, or programs that try to avoid overhead by
accessing the disk directly. These applications rely on specific
knowledge of the file or directory structure on the disk which
has changed with introduction of the ODS-5 structure.
Recommendations: Applications should use documented interfaces
and structures whenever possible.
4.2.3 – Supporting Long File Names
If an application does not handle extended names successfully,
examine the application for any the following:
o Does the application access and interpret the contents of
directory files directly? If so, the application may fail when
it encounters a directory that contains extended file names.
Recommendation: Modify the application to use the search
functions provided with the RMS or QIO interface, or with
LIBRTL routines such as LIB$FIND_FILE.
o Does the application attempt to parse or assume knowledge
of the syntax of a file specification? For example, the
application might search for a bracket ([) to locate the
beginning of a directory specification, or for a space
character to mark the end of a file specification.
Recommendation: The application should rely on RMS to
determine whether a file specification is legal rather than
pretesting the actual name. Use the NAM$L_NODE, NAM$L_DEV,
NAM$L_DIR, NAM$L_TYPE, and NAM$L_VER fields of the NAM block
or SYS$FILESCAN to retrieve this information.
o Does the application depend on the NAM$V_DIR_LVLS bits in the
NAM$L_FNB field to determine how many directory levels there
are in the current file specification? Because there are only
three bits in this field, it can only specify a maximum of
eight levels. Applications seldom use these bits; they are
mainly used by RMS when a NAM is specified as a related file
specification.
Recommendation: Starting with OpenVMS Version 7.2, there is
a new larger field available in both the NAM and the NAML
blocks, NAM$W_LONG_DIR_LEVELS. Use this field to locate the
correct number of directory levels.
o Does the application rely on the NAM$V_WILD_UFD and SFD1 -
SFD7 bits to determine where there are wildcard directories?
Because there are only eight of these bits they can only
report wildcards in the first eight directory levels.
Applications seldom use these bits; they are mainly used by
RMS when a NAM is specified as a related file specification.
Recommendation: Starting with OpenVMS Version 7.2, there is
a new field available in both the NAM and NAML block, NAML$W_
FIRST_WILD_DIR. Use this field to locate the highest directory
level where a wildcard is to be found.
o Does the application use the QIO interface to the file system
and specify or request a file name from QIO directly? The
QIO interface requires that an application specify explicitly
that it understands extended file names before it will accept
or return the names. In addition, the file name format for
extended file names is not identical between RMS and the QIO
interface. Additionally, some file names may be specified in
2-byte Unicode (UCS-2) characters. Your application must be
capable of dealing with 1 character that spans 2 bytes.
Recommendations: Most applications that use the QIO interface
also use RMS to parse file specifications and retrieve the
file and directory ID for the file. They then use these ID
values to access the file with the QIO interface. This method
of access continues to work with extended names. DIGITAL
recommends changing to this method to fix problem.
You can also obtain the name that the QIO system uses from
the NAML$L_FILESYS_NAME field of a NAML block, or use the new
system service (SYS$CVT_FILENAME) to convert between the RMS
and the QIO file name. In this case, you will also need to
provide an expanded FIB block to the QIO service to specify
that your application understands extended names, expand your
buffers to the maximum size, and prepare to deal with 2-byte
Unicode characters.
4.2.4 – Upgrading to Full Support
Some OpenVMS applications, such as system or disk management
utilities, may require full support for Extended File
Specifications. Typically these are utilities that must be able
to view and manipulate all file specifications without DID or
FID abbreviation. To upgrade an application so that it fully
supports all the features of Extended File Specifications, do the
following:
1. Convert all uses of the RMS NAM block to the new NAML block.
2. Expand the input and output file name buffers used by RMS.
To do this, use the NAML long_expanded and long_resultant
buffer pointers (NAML$L_LONG_EXPAND and NAML$L_LONG_RESULT)
rather than the short buffer pointers (NAML$L_ESA and NAML$L_
RSA), and increase the buffer sizes from NAM$C_MAXRSS to
NAML$C_MAXRSS.
3. If long file names (greater than 255 bytes) are specified in
the FAB file name buffer field (FAB$L_FNA), use the NAML long_
filename buffer field (NAML$L_LONG_FILENAME) instead. If long
file names are specified in the default FAB name buffer field
(FAB$L_DNA), use the default NAML name buffer field (NAML$L_
LONG_DEFNAME) instead.
4. If you use the LIB$FIND_FILE, LIB$RENAME or LIB$DELETE
routines, set LIB$M_FIL_LONG_NAMES in the flags argument
(flags is a new argument to the LIB$DELETE routine). Note
that you can use the NAML block in place of the NAM block to
pass information to LIB$FILE_SCAN without additional changes.
5. If you use the LIB$FID_TO_NAME routine, the descriptor for
the returned file specification may need to be changed to
take advantage of the increased maximum allowed of 4095
(NAML$C_MAXRSS) bytes.
6. If you use the FDL$CREATE, FDL$GENERATE, FDL$PARSE, or
FDL$RELEASE routine, you must set FDL$M_LONG_NAMES in the
flags argument.
7. Examine the source code for any additional assumptions made
internally that a file specification is no longer than 255
8-bit bytes.