This glossary defines data CENTURY. A period of 100
processing and communication terms consecutive years.
used in this publication.
Although IBM recognizes that the
21st century begins at 0000 hrs, 1
+----------+ January 2001, for purposes of this
| NUMERICS | document, we are defining the
+----------+ 20th--21st century boundary to be
between 2400 hrs, 31 December
2-DIGIT-YEAR FORMAT. A format that 1999 and 0000 hrs, 1 January 2000.
provides a year date as two digits This allows a discussion of the 21st
only to represent a year within a century to include all dates with a
specific century. The two 20yy format inclusive of the year
high-order digits of the year are 2000. Hence, the year 2100 is
truncated; for example "1995" is likewise relegated to the 22nd
represented as "95", and "00" century.
represents years ..."1800", "1900",
"2000".... CENTURY BYTE. The high order byte
of a field used to contain the two
4-DIGIT-YEAR FORMAT. A format that high order digits of a 4-digit year.
provides a year date as four digits: (For example, 19 in 1995, 20 in 2000
the two high-order digits represent and 2001).
the century and the two low-order
digits represent the year within the COSMETIC. Referring to a
century. For example, "1995" 2-digit-year date that is viewed by
represents the year 1995; "2095" human eyes only, such as a print
represents the year "2095". date on hardcopy output or a date on
a selection panel. Because it is
neither read nor further processed
+---+ by a program you might be able to
| C | exclude its modification from your
+---+ year2000 work effort.
CCYY FORMAT. A 4-digit-year format
that uses two century digits (CC) to +---+
indicate the century and two year | E |
digits (YY) to indicate the year +---+
within the century. The CC
representation is provided as either EXTERNAL SIDE. The receiver of a
the actual century digits (for data entity. Used in this document
example, 18, 19, or 20) or as a to mean a module or routine that
encoded value (for example, as 00 to accepts a 2- or 4-digit-date format
represent 19, 01 to represent 20 as entity for further processing from
in, "0095" represents the year another module or routine.
"1995" and "0195" represents the
| F | | L |
FIXED WINDOW. A technique to LEAP YEAR. A year either evenly
determine the century (high-order divisible by 400 OR evenly divisible
digits) of a year when represented by 4 and not evenly divisible by
by two digits. The 2-digit year is 100. For example, the year 1900 was
compared against a hardcoded not a leap year but the year 2000 is
threshold. The century designation a leap year.
is limited to a 100-year range
spanning only two centuries. For LILIAN DATE. The number of days
example, assume the threshold is 60, since 14 October 1582. 15 October
then if the 2-digit year is ò60, the 1582 is Lilian day 1, 16 October
year is in the 20th century; if the 1582 is Lilian day 2, and so on.
2-digit year is <60, the year is in (Named for Aloysius Lilius (an
the 21st century. advisor to Pope Gregory XIII) who,
together with his brother,
constructed the current Gregorian
| G |
GREGORIAN CALENDAR. Today's | R |
general-use calendar of 12 months +---+
and 365 days that employs the
current leap year algorithm (refer ROLLING WINDOW. Synonymous with
to LEAP YEAR below). SLIDING WINDOW.
| I | | S |
INTERNAL SIDE. The creator or SLIDING WINDOW. A technique to
manipulator of a data entity. Used determine the century (high-order
in this document to mean a module or digits) of a year when represented
routine that externalizes a 2- or by two digits. The user specifies
4-digit-year format entity to the number of years (both past and
another module or routine. future) within a 100-year window
spanning two centuries. For
example, assume the window is set at
+---+ 19 future years (1996-2014) and 80
| J | past years (1915-1994). Dates in
+---+ the range "00-14" (inclusive) are
designated 21st century dates
JULIAN DATE. A date in the format because they fall into the future
YYDDD. A date format that contains window. Dates in the range "15-99"
the year in positions 1 and 2, and (inclusive) fall into the 20th
the day in positions 3 through 5. century.
The day is represented as 1 through
366, right adjusted, padded with
zeroes on the left.
+---+ YEAR2000 READY. The capability of a
| T | software program to correctly
+---+ interpret and manipulate year-date
data outside the 1900-1999 year
TRANSFORMATION 2000. IBM's range and produce valid arithmetic
Information Systems Solution results.
Corporation (ISSC) comprehensive set
of solutions that takes into account YEAR2000 TRANSITION. The process of
applications, systems software and revising all programming entities
hardware in both a centralized (programs, databases, and so on) to
and/or distributed environment. correctly process date data outside
the range 1900-1999.
+---+ YY FORMAT. Synonymous with
| Y | 2-DIGIT-YEAR FORMAT.
YYYY FORMAT. Synonymous with
YEAR2000 CHALLENGE. The work-effort 4-DIGIT-YEAR FORMAT and a subset of
required to complete a Year2000 CCYY FORMAT.
transition, to include planning,
identifying, reformatting, testing,
and migrating phases. +----------+
| NUMERICS |
YEAR2000 PROBLEM. The potential +----------+
problems and its variations that
might be encountered in any level of 20TH CENTURY. The period of time
computer hardware or software from 0000.00 hrs 1 January 1901 through
microcode to application programs, 2400.00 hrs 31 December 2000.
files, and databases that need to
correctly interpret year-date data 21ST CENTURY. The period of time
represented in 2-digit-year format. 0000.00 hrs 1 January 2001 through
2400.00 hrs 31 December 2100.