Technical data

Using Files and Directories
10.1 Understanding Extended File Specifications Features
Feature Description
New on-disk structure Extended File Specifications support the latest volume On-
Disk Structure (ODS): Level 5 (ODS-5). This volume structure
provides the basis for creating and storing files with extended
file names.
Additional character
set support
A broader set of characters is available for naming files on
OpenVMS. Extended File Specifications offers support for file
names that use the 8-bit ISO Latin-1 character and 16-bit
Unicode (UCS-2) character sets.
Extended file naming File names can now exceed the traditional 39.39 character limit
up to a maximum of 236 bytes.
Case preservation Extended File Specifications preserve the case of file
specifications created with ODS-5 attributes. However, the
system still performs case-insensitive string matching.
Deep directory levels To support deep directory levels, the length of directory
specifications has been extended to a maximum of 512
characters.
For more information about each feature, refer to OpenVMS Guide to Extended
File Specifications.
10.1.1 Using Extended File Specifications
Beginning with OpenVMS Version 7.2, RMS allows you to use directory levels
deeper than 8 as well as the new RMS API extensions on both ODS-2 and ODS-5
volumes by default. However, you can create extended file names only on an
ODS-5 volume. Section 9.3.3 and Section 9.5.5.1, respectively, explain how to
create a new ODS-5 volume and how to convert an ODS-2 volume to an ODS-5
volume.
Once you change a volume to ODS-5, your programs can create and read extended
file names. However, by default, DCL (as well as some applications) does not
accept all extended names.
1
DCL also capitalizes any lowercase file names that
users enter at the command line prompt.
2
Enabling the Extended File Specifications Parsing Feature
For DCL to accept all extended file names, you must enable the Extended File
Specifications file name parsing feature. On OpenVMS Alpha systems, you can
instruct DCL to accept ODS-5 file names on a per-process basis by entering the
following command:
$ SET PROCESS/PARSE_STYLE=EXTENDED
After you enter the command, DCL accepts a file name similar to the following:
$ CREATE MY^[FILE
For more details on setting parse styles, refer to the OpenVMS DCL Dictionary.
The OpenVMS Record Management Services Reference Manual contains
additional information about RMS default Extended File Specifications features.
1
Even with the TRADITIONAL parse style, DCL allows some ODS-5 file names; for
example, DCL accepts x.x.x.
2
Some applications also use DCL internally to read file names that users type after an
application prompt.
10–2 Using Files and Directories