HP OpenVMS Systems Documentation
OpenVMS User's Manual
access control entry (ACE): An entry in an access
control list. Access control entries may specify identifiers and the
access rights to be granted or denied to the holders of the
identifiers, default protection for directories, or security alarm
access control list (ACL): Collection of entries that
define the access rights a user or group has to a protected system
access control string: A series of 0 to 42 characters
that contains login information to be sent to a remote node. On OpenVMS
systems, an access control string usually consists of a user name,
spaces or tabs, and a password.
account: Every user must have an account to use the
system. The account is identified by the user's user name. Different
accounts allow different levels of service from the system (for
example, the privileges users hold, the times during which they can log
in, and so on).
American Standard Code for Information Interchange
(ASCII): A set of 8-bit binary numbers representing the
alphabet, punctuation marks, numerals, and other special symbols used
in text representation and communications protocol.
ASCII: See American Standard Code for Information
assignment statement: In DCL, the association of a
symbol name with a character string or numeric value. Symbols can
define synonyms for system commands or can be used as variables in
batch job: A program that is scheduled and executed
under the control of the batch processing subsystem. Control input for
a batch job comes from a command procedure stored on disk and output is
directed to a disk file.
best-effort delivery: Network protocol that attempts
to deliver data but does not try to recover if there is an error such
as a line failure.
break-in attempt: An effort made by an unauthorized
source to gain access to the system. Because the first system access is
achieved through logging in, break-in attempts primarily refer to
attempts to log in illegally. These attempts focus on supplying
passwords for users known to have accounts on the system through
informed guesses or other trial-and-error methods.
buffer: An internal memory area used for temporary
storage of data records during input or output operations.
captive account: A type of OpenVMS account that limits
the activities of the user. Typically, the user is restricted to using
certain command procedures and commands. For example, the user may not
be allowed to use the Ctrl/Y key sequence. This type of account is
synonymous with a turnkey or a tied account.
central processing unit (CPU): The hardware that
handles all calculating and routing of input and output as well as
executing programs. In short, the CPU is the part of the computer that
character string: A contiguous set of printable
collating sequence: An order assigned to the
characters of a character set (for example, ASCII, Multinational, or
EBCDIC) used for sequencing purposes.
command: In DIGITAL Command Language (DCL), an
instruction, generally an English word, entered by the user at a
terminal or included in a command procedure. A command requests that
the software monitoring a terminal or reading a command procedure
perform some well-defined activity. For example, entering the COPY
command requests that the system copy the contents of one file into
command image: A program associated with and invoked
by a DCL command.
command interpreter: A procedure-based system code
that executes in supervisor mode in the context of a process to
receive, to check the syntax of, and to parse commands entered by the
user at a terminal or submitted in a command file.
command level: Input stream for the command
interpreter. The initial input stream is always command level 0. An
interactive command procedure begins executing at command level 1. A
batch job command procedure begins executing at command level 0. You
can use the execute procedure (@) command or the CALL command in a
command procedure to create up to 32 nested command levels.
command parameter: The positional operand of a command
delimited by spaces, such as a file specification, an option, or a
command procedure: A file containing commands and data
that the command interpreter can accept. Because command procedures
provide a means of automatically passing commands to the operating
system, users do not have to manually enter those commands at a
terminal. In addition, command procedures permit users to employ such
programming techniques as loops, counters, labels, and symbol
substitution to set up elaborate command sequences that can be altered
through user interaction. Command procedures can also be submitted to
the system for processing as batch jobs.
command string: A line (or set of continued lines)
containing a command and, optionally, information modifying the
command. A command string consists of a command, its qualifiers, its
parameters (file specifications, for example), and their qualifiers. A
command string is normally terminated by pressing the Return key.
compound character: A combination of simple characters
and characters from the extended character set.
concatenate: The act of linking files together in a
CPU: See central processing unit.
cursor: An indicator used on a monitor screen to point
to a location on the screen.
data: A general term referring to any representation
of facts, concepts, or instructions in a form suitable for
communication, interpretation, or processing.
DCL (DIGITAL Command Language): A command interpreter
in an OpenVMS system that provides a means of communication between the
user and the operating system.
DECnet-Plus: Family of Compaq hardware and software
products that implement the Digital Network Architecture (DNA) Phase V,
which integrates OSI and DNA protocols. DECnet-Plus is compliant with
OSI and compatible with DECnet Phase IV and TCP/IP.
default: A value or operation that is automatically
included in a command, unless the user specifies otherwise. In most
cases, default settings will be what is "normal" or
default directory: The directory that the OpenVMS
operating system assumes when a directory specification has not been
supplied by the user.
default disk: The disk from which the system reads and
to which the system writes; by default, all files that you create. The
default is used whenever a file specification in a command does not
explicitly name a device.
delimiter: A character that separates, terminates, or
organizes elements of a character string, statement, or program.
detached process: A process that has no owner. The job
controller creates a detached process when a user logs in to the
system. It also creates a detached process each time it initiates a
batch job or services a request for a logical link connection. Because
the job controller does not own the processes it creates, these
processes are referred to as detached. The DCL command RUN/UIC and the
Create Process system service (specifying a UIC) allow a suitably
privileged process to request creation of a detached process.
device: The general name for any peripheral connected
to the processor that is capable of receiving, storing, or transmitting
data. Card readers, line printers, and terminals are examples of
record-oriented devices. Magnetic tape devices and disk devices are
examples of mass storage devices. Terminal line interfaces and
interprocessor links are examples of communications devices. Devices
are not necessarily hardware.
device name: The field in a file specification that
identifies the device unit on which a file is stored. Device names also
include the mnemonics that identify an I/O peripheral device in a data
transfer request. A device name consists of a mnemonic followed by a
controller identification letter (if applicable), a unit number (if
applicable), and a colon.
DIGITAL Command Language (DCL): See DCL (DIGITAL
directory: A file that briefly catalogs a set of files
stored on disk or tape. The directory includes the name, type, and
version number of each file in the set, as well as a unique number that
identifies the file's actual location and points to a list of its
attributes. See also subdirectory.
disk: High-speed, random-access devices. There are
several kinds of disks. Floppy disks are small, flexible disks. Hard
disks are either fixed in place or removable. Removable disk types
include a single hard disk enclosed in a protective case and a stacked
set of disks enclosed in a protective case.
editor: A program used to create or modify text in a
equivalence string: The string associated with a
logical name in a logical name table. An equivalence string can be, for
example, a device name, another logical name, or a logical name
concatenated with a portion of a file specification.
error message: A message sent by the system when some
action you have requested fails. Each error message identifies the
particular part of the operating system that detected the error. Most
error messages result from typing mistakes or mistakes in specifying
syntax. Often, you can correct the error by retyping the command
executable image: An image that can be run in a
process. When run, an executable image is read from a file for
execution in a process.
expression: Any combination of variables, constants,
or both, with operators that the computer can evaluate to produce a
Extended File Specifications: An optional feature that
removes many of the directory and file-naming restrictions previously
imposed by OpenVMS. Allows deep directories and extended file names.
field: A set of contiguous bytes in a logical record.
file: A set of data elements arranged in a structure
significant to the user. A file is any named and stored program, data,
or both, to which the system has access. Access can be of two types:
read-only, meaning the file is not to be altered, and read/write,
meaning the contents of the file can be altered. See also
file name: The field containing a 1- to 39-character
name for a file that precedes the file type in a file specification.
file path: The disk and directory portions of a file
file specification: A unique name for a file on mass
storage media. It identifies the node, the device, the directory name,
the file name, the file type, and the version number under which a file
file type: The field in a file specification that
consists of a period followed by a 0- to 39-character identification.
By convention, this field identifies a generic class of files that have
the same use or characteristics, such as compiler and assembler listing
files, binary object files, and so on.
folder: A subdivision of a file in which you can store
foreign command: A symbol that executes an image whose
name is not recognized by the command interpreter as a DCL command.
foreign file specification: A file whose specification
does not conform to OpenVMS syntax or format.
full name: Complete specification of a name in the
DECdns namespace, including all parent directories in the path from the
root directory to the object, directory, or soft link being named; can
also include a namespace name, but not necessary when only one
namespace exists in a network.
function keys: Keyboard keys that send special signals
to the operating system. Function keys are referred to as Fn,
where n is the number associated with that key. For example,
by pressing F9 in Mail you are telling the system you want to forward a
generic device name: A device name that identifies the
type of device but not a particular unit; a device name in which the
specific controller or unit number is omitted.
global symbol: Either of the following:
hardware device: The physical computer equipment,
including such mechanical devices as the line printer, the terminals,
the mass storage devices, and so forth.
hardcopy terminal: Terminals that print output on
paper. See also terminal.
help: A text file in a format suitable for use with
the HELP command. Online help can provide up to nine levels of search.
hierarchical directory structure: A structure of
directories that has several levels arranged in a tree-like structure,
based on a one-to-many relationship.
high-performance Sort/Merge utility: Version of the
Sort/Merge utility available on OpenVMS Alpha systems.
host: A system connected to a network. See also
identifier: An alphanumeric string representing a user
or group of users recorded in the rights database and used by the
system in checking access requests. There are four types of
identifiers: environmental, facility, general, and user identification
image: The procedures and data bound together by the
linker to form an executable program. This executable program is
executed by the process. There are three types of images: executable,
shareable, and system.
indexed sequential file: A record file in which each
record has one or more data keys embedded in it. Records in the file
are individually accessible by specifying a key associated with the
input file: A file containing data to be transferred into the computer.
Often input and output files are confused. DCL usually prompts for
these files, but most system utilities require you to identify your
input and output files by position in a command line. Be sure of the
syntax, or format, for the command you are using.
input stream: The source of commands and date---the
user's terminal, the batch stream, or a command procedure.
interactive mode: The mode of communication with the
operating system in which you enter a command and the system executes
it and responds. One command has to finish executing before you can
iterative translation: The repetitive translation of a
logical name that occurs when a logical name's definition includes
another logical name.
job: The accounting unit equivalent to a process and
its subprocesses, if any, and all subprocesses that they create. Jobs
are classified as batch and interactive. For example, the job
controller creates an interactive job to handle a user's requests when
the user logs in to the system and it creates a batch job when the
symbiont manager passes a command input file to it.
job tree: A hierarchy of all processes and
subprocesses, with the main process at the top.
key: One of the following:
keyboard: An input device that can be operated
similarly to a typewriter.
keypad: The small set of keys next to the main
keyboard on a terminal.
keyword: A word reserved for use in certain specified
syntax formats, usually in a command string or a statement.
lexical function: A command language construct that
the DIGITAL Command Language (DCL) command interpreter evaluates and
substitutes before it parses a command string. Lexical functions return
information about the current process (the user identification code
(UIC) or default directory, for example) and about character strings
(their length or the location of substrings, for example).
line editor: A program that allows you to make
additions and deletions to a file line by line.
line printer: An output device that prints files one
line at a time. It is used for printing large amounts of output that
would otherwise tie up a slower device. Almost every system has a
device designated as the line printer. In some cases, the "line
printer" is actually a high-speed terminal.
local node: The network node at which the user is
local symbol: Either of the following:
logging in: The identification of a user to the
system. When users log in, they type a user name and password in
response to prompts from the system. If the user name and the password
match an account on the system, the user is allowed access to the
logging out: The process of entering the DIGITAL
Command Language (DCL) command LOGOUT, which informs the operating
system that the user has finished using a particular terminal.
logical device name: A character string that equates a
somewhat cryptic device name to a short, meaningful name.
logical expression: An expression that has a true or
logical name: A user-specified name that can be used
in place of another character string to represent system objects such
as files, directories, devices, and queues. Logical name assignments
are maintained in logical name tables.
logical name table: A table that contains a set of
logical names and their equivalence strings. A logical name can be
process private or shareable. The default shareable logical name tables
are job, group, system, clusterwide system, and clusterwide parent
login class: User's method of logging in to the
system. System managers can control system access based on the login
class: local, dialup, remote, batch, or network.
login command procedure: A command procedure that is
automatically executed at login and at the beginning of a batch job.
login directory: The default directory established by
LOGINOUT when a user logs in.
magnetic tape: A medium on which data can be stored
mass storage device: An input/output device on which
data and other types of files are stored while they are not being used.
Typical mass storage devices include disks, magnetic tapes, and floppy
master file directory (MFD): A file that contains the
main directory for a disk.
memory: A series of physical locations into which data
or instructions can be placed in the form of binary words. Each
location in memory can be addressed and its contents can be altered.
Memory should not be confused with mass storage devices.
Multipurpose Internet Mail Extension (MIME): The
standard used to attach nontext files to mail messages. Nontext files,
such as graphics or sound files, are encoded and sent as plain text,
although that text may not be readable. The recipient can decode the
text into the file's original format using a MIME interpreter utility.
network: A collection of interconnected, individual
node: One of the following:
node specification: The first field in a file
specification. This field identifies the location of a computer system
in a network.
null value: A string with no characters that is
represented in a command procedure by two quotation marks (" ").
numeric expression: A mathematical statement
consisting of a collection of operands connected by arithmetic
object: A passive repository of information to which
the system controls access. Access to an object implies access to the
information it contains.
open account: An account that does not require a
operand: The part of an expression that contains a
value. Operands are acted on by operators during expression evaluation
to produce a result.
operating system: An integrated collection of programs
that controls the execution of computer programs and performs system
operator: The part of an expression that tells the
computer how to manipulate the operands. For example, the plus sign (+)
is an operator that tells the computer to perform addition.
output file: A file that contains the results of a
processing operation; for example, a file that has been sorted or
parameter: Either of the following:
parsing: Either of the following:
password: A character string that users provide at
login time to validate their identities and as a form of proof of their
authorization to access their accounts. There are two kinds of
passwords---system passwords and user passwords. User passwords include
both primary and secondary passwords.
personal login command procedure: A command procedure
that lets you customize your computing environment. The commands
contained in it are executed every time you log in.
physical device name: A character string that uniquely
identifies a physical device (such as a storage disk or a terminal) to
primary password: A type of user password that is the
first user password the system requests from the user. Systems may
optionally require a secondary password as well. The primary password
must be the password that is associated with the user name.
print form: A set of attributes that defines page set
up and stock for printing.
print queue: A list of files waiting to be printed.
priority: A rank assigned to a process to determine
its precedence in obtaining system resources when the process is
private volume: A mass storage media that has been
allocated by a process for its own exclusive use.
process: The basic entity scheduled by the system
software. A process provides the context in which an image executes. A
process consists of an address space and both hardware and software
process default directory: The system automatically
makes your top-level directory your process default directory when you
program: A series of instructions aimed at a
particular result. Programming languages are a means of describing
procedures so that they can be performed by a computer. See also
program stub: A temporary section of code that is used
during the testing phase of writing command procedures. A program stub
usually outputs a message stating the procedure it is replacing.
prompt: A character string appearing on a terminal
screen indicating that the user must provide input.
protected object: An object containing shareable
information to which the system controls access. See also
protection code: A series of letters that specify what
access different categories of system users can have to a file or to
another protected object and what they can do to it when they access it.
proxy login: A type of login that permits a user from
a remote node to effectively log in to a local node as if the user
owned an account on the local node. However, the user does not specify
a password in the access control string. The remote user may own the
account or share the account with other users.