VMS Help
Ext File Specs, Overview, Impact
*Conan The Librarian
|
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.
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.
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)
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.
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.
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.
|
3 - File System (XQP) Changes
|
The following Files-11 Extended QIO Processor (XQP) file system
enhancements are offered under Extended File Specifications
through the $QIO interface. Note that in some cases, XQP file
format rules may differ from those that apply to other system
services that accept file names, such as those provided by RMS.
o The current restrictions on the format and content of file
names have been modified, specifically:
- The 39.39 file name length restriction was removed to allow
longer file names, up to 236 8-bit characters or 117 16-bit
characters
- The use of characters from the ISO Latin-1 multinational
character set is supported in file specifications
- Support for the entry and storage of file and directory
specifications in Unicode.
|
4 - DCL Commands and Utilities
|
In DCL commands, you can select either of the following styles
for parsing file specifications:
o Traditional filenames are allowed on both ODS-2 and ODS-5
volumes.
o Extended filenames are allowed on ODS-5 but not on ODS-2
volumes.
Some OpenVMS commands and utilities have new qualifiers to
control the interpretation and display of file specifications.
NOTE
DCL lexical functions use the DEC-Multinational character
set, which is different from the ISOLatin-1 character set
used for file names on an ODS-5 disk. This can lead to
unexpected results if, for example, you use the DCL function
F$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.
|
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.
|
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