TS/MP 2.5 System Management Manual

DBCS See double-byte character set (DBCS).
DDL See Data Definition Language (DDL).
deadlock A situation in which two processes cannot proceed because each is waiting for a reply from
the other.
1.
2. A situation in which two transactions cannot proceed because each is waiting for the other
to release a lock.
dedicated device A term formerly used for a terminal or other input/output device controlled by a configured TERM
object, so that a Pathway application always ran on that device without having to be started
from PATHCOM with a RUN PROGRAM command. (No new term replaces this term; instead, the
manual text now refers to such devices as those associated with configured TERM objects.) See
also nondedicated device and configured TERM object.
default value The value that the system uses for a particular attribute or parameter when a value has not been
supplied by the user.
DEFINE A named set of attributes and associated values. In a DEFINE (as with an ASSIGN command),
users can specify information to be communicated to processes they start.
definition files A set of files containing data declarations for items related to SPI messages and their processing.
The core definitions required to use SPI are provided in a DDL file and in several language-specific
definition files, one for each programming language that supports SPI. The Tandem DDL compiler
generates the languagespecific files from the DDL file. Subsystems that support SPI provide
additional definition files containing subsystem-specific definitions.
delimiters Characters that make it possible for a SCREEN COBOL requestor and an external device or
front-end process to exchange compact variable-length messages efficiently; delimiters can be
message delimiters or field delimiters.
descriptor For each elementary data item, the SCREEN COBOL compiler builds a data structure that describes
the size, type, usage, and dependencies of the item. All of the information that pertains to a given
item makes up the descriptor for that item. For example, the PICTURE specification is included in
the descriptor. The descriptors are passed to the TCP in the pseudocode and provide a dictionary
of information for interpreting and handling incoming data. When the MAP or SMAP compiler
option is used, the descriptors appear in the compiler map at the end of the listing.
diagnostic screen A screen of information that is displayed to inform the terminal operator of error conditions and
termination status.
disk process In the Tandem environment, the portion of the operating-system software that performs read, write,
and lock operations on disk volumes and creates TMF audit records. See also file system.
display attribute A terminal display feature that is given a screen data name. The screen data name can be
associated with a predefined system name in the SPECIAL-NAMES paragraph and thus be
manipulated by a SCREEN COBOL program.
distributed data Information (for example, customer names and addresses, inventory items, and personnel records)
that resides on more than one node in a network and can be accessed by authorized users from
any node in that network.
distributed
processing
A type of processing environment in which resources are distributed among CPUs within a single
system or spread across a network of systems. A user on any network node can, if properly
authorized, access resources and database files anywhere within the network.
Distributed
Systems
Management
(DSM)
A group of tools for managing a variety of subsystems in a distributed processing environment.
distributed
transaction
processing (DTP)
The coordination of transactions among application servers residing within an Expand network
and possibly accessing different database management systems (NonStop SQL/MP and Enscribe).
DTP allows the coordination of multiple, autonomous actions as a single logical unit of work.
double-byte
character
A character represented in two bytes. See also double-byte character set.
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