Lessons Learned in Implementing the Extended Date/Time Format in a Large Digital Library Dublin Core Metadata Initiative International Conference 2013 Wednesday, September 4

512,694 records (469,865 public)

[between ] [between 1846 and 1848]

November 18, 19, 20, 1971

[either 1581 or 1587]

[1889 and 1891]

early 1900s

[1900?] [190-?] [19--]

c. [1900] [1900]-02-13

around 1920 (?)

1626 [i.e. 1676]

About EDTF

ISO 8601 YYYYMMDDYYYY-MM-DD BasicExtended

ISO 8601 YYYYMMDDYYYY-MM-DD BasicExtended Extended Date/Time Format

ISO 8601 EDT F YY (century) YYuu

Evaluation

February 2013: 379,392 public records 390,751 date values 55,212 unique dates

Level 0: 377,059 dates

Date: 1909

Date:

Date:

Date: T10:54:19

Date: 1874/1875

Level 1: 2,609 dates

Date: 1930?

Date: 1860~

Date: 1621?~

Date: 191u

Date: 1980~/1990~

Year Exceeding Four Digits (L1) y y

Date:

Level 2: 14 dates

Date: 1902?-05-(06)?

Date: 185u-10

Date: [ ]

Date: [..1909]

Multiple Dates {1667, 1668, } {1960, }

Masked Precision 196x 19xx

Extended Interval (L2) (01)~/ (20)~ uu/

Year Exceeding Four Digits – Exponential Form y17e7 y17101e4p3

Season - Qualified ^southernHemisphere

Non-EDTF-Valid Dates

Metadata Creators

End Users

>> August 23, 1937

>> Spring 1956

[ ] >> Between August 3, 1989 and August 6, 1989

1905-uu-03 >> ______ 3, 1905 ?? 3, 1905 [month unknown] 3, 1905

? >> June 1938? Possibly June 1938 June 1938 (uncertain)

uu

uu >>

Why EDTF?

Potential Challenges * Some dates will still be difficult (e.g., “early 1900s”) * Does not match ISO 8601 exactly and is not yet formally-accepted standard * EDTF dates are not always understandable to users * May conflict with external standards and local practice (e.g., use of square brackets in library cataloging)

Pros * Standardized ways of representing many complex dates found in cultural heritage collections * Some overlap with ISO 8601 and compatible with W3C Date and Time formats (existing dates may already be valid) * Machine-readable * Flexible implementation options * Active community discussing usage * Already supported by Library of Congress standards

Some References Library of Congress Extended Date/Time Format (EDTF) 1.0: UNT Libraries Metadata Guidelines for Dates: UNT EDTF Validator: Tarver, Hannah (2013). [Handout to Accompany Poster on Implementation of a New Date/Time Standard]: Tarver, Hannah & Mark Phillips (2013). Lessons Learned in Implementing the Extended Date/Time Format in a Large Digital Library:

Questions?