+---+
       | D |
       +---+

DATA DEFINITION

An executable statement where a variable is assigned a
value.(BCS)

DATA DEFINITION C-USE COVERAGE

The percentage of data definition C-use pairs in a
component that are exercised by a test case suite.(BCS)

DATA DEFINITION C-USE PAIR

A data definition and computation data use, where the
data use uses the value defined in the data
definition.(BCS)

DATA DEFINITION P-USE COVERAGE

The percentage of data definition P-use pairs in a
component that are exercised by a test case suite.(BCS)

DATA DEFINITION P-USE PAIR

A data definition and predicate data use, where the
data use uses the value defined in the data
definition.(BCS)

DATA DEFINITION-USE COVERAGE

The percentage of data definition-use pairs in a
component that are exercised by a test case suite.(BCS)

DATA DEFINITION-USE PAIR

A data definition and data use, where the data use uses
the value defined in the data definition.(BCS)

DATA DEFINITION-USE TESTING

A test case design technique for a component in which
test cases are designed to execute data definition-use
pairs.(BCS)

DATA DUPLEXING

Is a specialized method for dealing with data base year
2000 problems, without changing the date fields of all
of the applications which reference the data.  Two
versions of a data base are created, with one version
containing the original two-digit date fields, and the
second or "cloned" version containing the same
information, but the date fields are expanded to
four-digit form.

Software applications whose date fields use four-digits
can run against the four-digit data base, while
software applications still using the older two-digit
date fields can run against the two-digit data base.

Obviously data duplexing requires a lot of work in
keeping both versions of the data base synchronized.
Data duplexing is a rather complex and expensive
strategy, but actually expanding the date fields in
data bases is one of the most troublesome and expensive
aspects of the year 2000 problem.
(CJ)

DATA FLOW COVERAGE

Test coverage measure based on variable usage within
the code.  Examples are data definition-use coverage,
data definition P-use coverage, data definition C-use
coverage, etc.(BCS)

DATA FLOW TESTING

Testing in which test cases are designed based on
variable usage within the code.(BCS)

DATA USE

An executable statement where the value of a variable
is accessed.(BCS)

DATE COUNTER OVERFLOW

The point in time at which the value contained in a
"date" variable causes a failure of a logical operation
within an application.  This misinterpretation of the
"date" value may be due to a roll-over (similar to an
odometer", by the value being interpreted as a negative
number, or by an "overflow" flag being set in a
processor status word.  Date counter overflows may
occur before, during, or after the Year 2000.
(IEEE)

DATE EXCHANGE

The interchange of date data between two or more system
or system elements.  In order to facilitate proper date
data exchange between two or more system or system
elements, defined formats should be identified and
documented by the suppliers of system or system
elements.  Such formats may include the standards
(see STANDARDS), other generally accepted industry
date representations, or other documented methods of
date representation.
(IEEE)

DATE PROCESSING

The handling of date data within a system or
system element
(IEEE)

DAYLIGHT SAVING TIME

Daylight Saving Time is achieved by advancing the clock
one hour.  Since 1987, Daylight Saving Time in all U.S.
states, the District of Columbia, and U.S. possessions
begins at 2 am on the first Sunday in Apr. and ends at
2 am on the last Sunday in Oct.  Daylight Saving Time
was first instituted in the Uniform Time Act, which
became effective in 1967.  At that time, all states,
the District of Columbia, and U.S. possessions were to
observe Daylight Saving Time beginning at 2 am on the
last Sunday in Apr. a nd ending at 2 am on the last
Sunday in October.  Any state could, by law, exempt
itself; a 1972 amendment to the act authorized states
split by time zones to take that into consideration in
exempting themselves.  Arizona, Hawaii, Puerto Rico,
the Virgin Is lands, American Samoa, and part of
Indiana are now exempt.  Some local zone boundaries in
Kansas, Texas, Florida, Michigan, and Alaska have been
modified by the Dept. of Transportation, which oversees
the act.  To conserve energy, Congress put most of the
n ation on year-round Daylight Saving Time for 2 years
effective Jan. 6, 1974, through Oct. 26, 1975, but
another bill, signed in Oct. 1974, restored Standard
Time from the last Sunday in that month to the last
Sunday in Feb. 1975.  At the end of 1975, Congr ess
failed to renew this temporary legislation, and the
nation returned to the older end-of-April to
end-of-October Daylight Saving Time system.  On July 8,
1986, Pres.  Ronald Reagan signed legislation moving up
the start of Daylight Saving Time to the first Sunday
in Apr.  The law was effective beginning in 1987.  The
Dept. of Transportation estimated that the earlier
starting date would help save m ore than $28 million in
traffic accident costs and prevent more than 1,500
injuries and 20 deaths annually.  (FW)


DEBUGGING

The process of finding and removing the causes of
failures in software.(BCS)

is the process of analysing and locating bugs when
software does not behave as expected.  Debugging is an
activity that supports testing, but cannot replace
testing. [Gerrard]

DECISION

A program point at which the control flow has two or
more alternative routes.(BCS)

DECISION CONDITION

A condition within a decision.(BCS)

DECISION COVERAGE

The percentage of decision outcomes that have been
exercised by a test case suite.(BCS)

DECISION OUTCOME

The result of a decision (which therefore determines
the control flow alternative taken).(BCS)

DESIGN-BASED TESTING

Designing tests based on objectives derived from the
architectural or detail design of the software (e.g.,
tests that execute specific invocation paths or probe
the worst case behaviour of algorithms).(BCS)

DESK CHECKING

The testing of software by the manual simulation of its
execution.(BCS)

DIRTY TESTING

See negative testing. [Beizer]

DNC

digital-numerically-controlled

DOCUMENTATION TESTING

Testing concerned with the accuracy of
documentation.(BCS)

DOMAIN

The set from which values are selected.(BCS)
DOMAIN

"a well-defined set of characteristics that accurately,
narrowly and completely describe a family of problems
for which computer application solutions are being, and
will be sought."  Domain analysis is defined as the
investigation of a specific application area to
identify the operations, objects and structures that
commonly occur in software systems within the area.
GRA95, p388 In data terms, the domain includes valid
value ranges, specific values, invalid values / ranges,
duplicates allowed / disallowed, default values,
conversion rules, null values allowed / disallowed.
GOR91.

DOMAIN TESTING

See equivalence partition testing.(BCS)

DYNAMIC ANALYSIS

The process of evaluating a system or component based
upon its behaviour during execution. [IEEE]

looks at the behaviour of software while it is
executing, to provide information such as execution
traces, timing profiles, and test coverage
information.[Gerrard]