IBM System/370 Operator's Reference Manual page 235

d
data management: Those parts of the control program that provide access to data sets,
enforce data storage conventions, and regulate the use of input/output devices.
data organization: The arrangement of a data set.
data protection: A safeguard invoked to prevent the loss or destruction of customer
data.
data security: A safeguard invoked to prevent the accessing of customer data.
data set: The major unit of data storage and retrieval in the operating system, consist-
ing of a collection of data in one of several prescribed arrangements and described by
control information that the system has access to.
data set control block (DSCB): A data set label for a data set in direct-access storage.
data set label (DSL): A collection of information that describes the attributes of a
data set, and that is normally stored with the data set; a general term for data set
control blocks and tape data set labels.
default value: A predetermined value used in place of an omitted entry.
deferred entry: An entry into a subroutine that occurs as a result of a deferred exit
from the program that passed control to it.
deferred exit: The passing of control to a subroutine at a time determined by an
asynchronous event rather than at a predictable time.
device independence: The ability to request input/output operations without regard to
the characteristics of the input/output devices.
device name: Usually, the general name for a kind of device, specified at the time the
system is generated. For example, 2314 or 3330 or TAPE. (See Unit name.)
direct access: Retrieval or storage of data by a reference to its location on a volume,
rather than relative to the previously retrieved or stored data.
diskette: A flexible magnetic oxide coated disk, permanently enclosed in a semi-rigid
protective plastic jacket approx. 8 inches square. During data processing operations the
disk turns freely within the jacket. It is capable of storing 1898 128-character data
records.
dispatching priority: A number assigned to tasks to determine the order in which they
will use the central processing unit in a multitask situation.
DTF (define the file) macro instruction: A macro instruction that describes the
characteristics of a logical input/output file, indicates the type of processing for the
file, and specifies the I/O areas and routines to process the file.
dump:
(1)
To print out the contents of all or part of virtual storage or of aux iliary
storage. (2) The data resulting from the process as in
(1) ..
dynamic address translation (DA
T): (1)
In S/370, the change of a virtual storage
address to an address in real storage during execution of an instruction. (2) A hard-
ware feature that performs the translation.
e
emulator: The combination of programming techniques and special machine features
that permits a given computing system to execute programs written for another
system.
entry
point: Any location in a program to which control can be passed by another
program.
environmental recording, editing, and printing (EREP): A program that processes the
data contained on the system recorder file.
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