Guardian Programmer's Guide

Table Of Contents
Glossary
Guardian Programmer’s Guide 421922-014
Glossary - 6
data space
data space. The area of virtual memory reserved for user data and system data.
DCT. See destination control table (DCT).
deadlock. A situation in which two processes or two transactions cannot continue because
they are each waiting for the other to release a lock.
DEFINE. An HP Tandem Advanced Command Language (TACL) command you can use to
specify a named set of attributes and values to pass to a process.
DEFINE name. An identifier preceded by an equal sign that can be used in place of an
actual name to identify a DEFINE in a procedure call. See DEFINE.
destination control table (DCT). A collection of operating system data structures that
serves as a directory of named processes and logical devices.
device subtype. A value that further qualifies a device type. For example, a device type of
4 indicates a magnetic tape drive; if the same device has a device subtype of 2, then
the magnetic tape drive has a 3206 controller. You can also apply a device subtype to
a process, for example, when performing terminal simulation.
disk drive. A device that stores and accesses data on a magnetic disk. Random access to
addressable locations on a magnetic disk is provided by magnetic read/write heads.
See also voluntary rendezvous opportunity (VRO).
disk volume. See voluntary rendezvous opportunity (VRO).
dispatching. The task of making a process active, permitting it to use the CPU to execute.
distributed system. A system that consists of a group of connected, cooperating
computers.
download. The process of transferring software from one location to another, where the
transferring entity initiates the transfer.
dynamic-link library (DLL). A collection of procedures whose code and data can be loaded
and executed at any virtual memory address, with run-time resolution of links to and
from the main program and other independent libraries. The same DLL can be used by
more than one process. Each process gets its own copy of DLL static data. Contrast
with shared run-time library (SRL). See also TNS/R library.
dynamic loading. Loading and opening dynamic-link libraries under programmatic control
after the program is loaded and execution has begun.
duplicate key. A sequence of characters that makes up the same value in a key field in
more than one record in the same file.
EDIT file. In the Guardian file system, an unstructured file with file code 101. An EDIT file
can be processed by either the EDIT or PS Text Edit (TEDIT) editor. An EDIT file