MARC PROPOSAL NO. 2009-01/1: New data elements in the MARC 21 Authority Format

1. BACKGROUND

Section 2 of RDA covers recording Attributes of Work and Expression and Section 3 covers recording Attributes of Person, Family and Corporate Body. RDA reflects those attributes and relationships as defined by the Functional Requirement for Authority Data (FRAD) in support of four user tasks: find, identify, contextualize, and justify.

In the RDA chapters that cover identifying attributes for person, family, corporate body, work, and expression, certain elements can be recorded either as part of the access point representing the entity, or as separate identifying elements, or both.

There are some elements that are not individually provided for in the MARC 21 Authority Format. They may currently be in a general subfield such as the 100 subfield $d for “dates associated with a name” or they may have been recorded in an unstructured note field, when they were recorded at all. Alignment with FRAD has also introduced a number of new elements that would not have been included in authority headings formulated according to AACR.

Discussion Paper 2008-DP04 (Encoding RDA, Resource Description and Access data in MARC 21) considered whether there was a need for specific content designation for additional elements specified in RDA or whether the information could be conveyed in unstructured notes. The MARC Advisory Committee agreed that i t was worth considering the addition of new data elements to the authority format, which would give the user the flexibility to use the granularity of RDA if desired.

Discussion Paper 2008-DP05/2 (New data elements in the MARC 21 Authority format) was presented to the MARC community in June 2008 at the MARC Advisory Meeting of the ALA Annual Conference in Anaheim, CA. It explored the issue further and suggested a number of elements to be added to the Authority Format. This document builds on this discussion paper and incorporates comments made at the meeting. It is structured in the same order of discussion than Discussion Paper 2008-DP05/2. However, the numbering is different.

2. DISCUSSION

2.1. Introduction

RDA defines separate elements for a number of attributes of the entities described in authority records. These attributes are recorded because they are part of the identity of the entity described, for example the language of the person. Some of these are also recommended for use as additions in the access points when needed to help identification and/or disambiguation. For example, Field of activity of the person is required by RDA for a person whose name consists of a phrase or appellation not conveying the idea of a person. For other persons, Field of activity is required when needed to distinguish a person from another person with the same name.

This paper proposes defining new data elements for attributes of persons, corporate bodies, families, works and expressions as defined in RDA. These attributes may also be needed in the access point for the entity. In the case where RDA instructs cataloguers to include a data element in the access points in order to identify and/or disambiguate, institutions implementing RDA in MARC 21 will have to decide whether to include the data element in the access point only or whether to record the information in one of the newly-created field or subfield as well as including it as addition to the name. If the attribute is not needed in the access point by one institution it may be needed by another, so inclusion of the data in the new fields in this proposal will create a richer and more flexible record.

This proposal covers primarily persons, corporate bodies, and families. More study is needed concerning additions to work and expression access points. Examples show usage according to RDA rules, but content formulated differently is possible in the proposed data elements.

2.2. Elements defined in RDA

Discussion Paper 2008-DP05/2 analysed, identified and grouped the RDA data elements for persons, corporate bodies, families, works and expressions to be defined into a number of categories:

• Dates
• Places
• Address
• Language
• Activities
• Gender
• Family information

Besides defining a special field for dates where structured date information is recommended, several fields contain a subfield for dates so that a period of time associated with the content of the field can be indicated. In the case of these special subfields, the date information may be unstructured. These data subfields are not in support of RDA, but have been added to the format for clarification.

The newly-defined MARC fields/subfields have been based on the RDA definitions, which have been included in each section. However, in some cases, those definitions have been broadened so that data recorded following other content standards than RDA can avail themselves of the new coding.

2.3. Dates

Discussion

Discussion Paper 2008-DP05/2 identified the following RDA data elements for special kinds of dates that are not already defined in the MARC 21 authority format and may be useful for entities expressed in authority records.

For a person:

• Date of birth is the year a person was born. Date of birth may also include the month and day of the person’s birth. (RDA 9.3.2.1)
• Date of death is the year a person died. Date of death may also include the month and day of the person’s death. (RDA 9.3.3.1)
• Period of activity is a date or range of dates indicative of the period in which a person was active in his or her primary field of endeavour. (RDA 9.3.4.1)

For a corporate body:

• A date associated with the corporate body is the date or range of dates on which a conference, etc., is held, or a date with which the corporate body is otherwise associated (e.g., date of founding). (RDA 11.4.1.1)
  • A date of establishment is the date on which an organization was established or founded (RDA 11.4.3.1)
  • A date of termination is the date on which an organization was terminated or dissolved (RDA 11.4.4.1)

For a family:

• A date associated with a family is a significant date associated with the family (RDA 10.4.1.1). It is required when needed to distinguish a family from another family with the same name.

These elements are required when needed to distinguish a person from another person with the same name, or a corporate body from another corporate body with the same name, or family from another with the same name.

Not considered here are dates associated with work and expression titles, and conference and treaty access points.

Discussion Paper 2008-DP05/2 suggested the creation of field 046 in the Authority format. This field is already available in the bibliographic format for Special coded dates and uses a structured form of date, making the data machine processible . However, many of the subfields are not appropriate for the authority format. Since MARC 21 attempts to define the same field for the same type of data across formats, it was decided to use field 046 but to choose different subfields from those available in the bibliographic format.

Field 046 includes subfields allowing the recording of all the types of dates listed above. Nnote that Start period and End period is to be interpreted broadly: subfield $o start period is used to record period of activity (start) and date of establishment; subfield $p End period is used to record period of activity (end) and date of termination. They are also used to record dates relating to families.

In order for these dates to be machine-processed, it is suggested that the dates should be encoded in a standard structured way, using an ISO 8601 compliant format. A profile for use of ISO 8601, with extensions needed by the community, has been developed and adopted by the PREMIS Editorial Committee. Use of that profile is recommended. See http://www.loc.gov/standards/datetime and Appendix A in this paper.

Proposed change

1. Define Field 046 in the Authority format as follows:

• 046 – SPECIAL CODED DATES (R)
  • Indicators
    • Both indicators are undefined; each contains a blank (#)
  • Subfield Codes
    • $f – Birth date (NR)
    • $g – Death date (NR)
    • $o – Start period (NR)
    • $p – End period (NR)
    • $6 – Linkage (NR)
    • $8 – Field link and sequence number (R)

Examples

046 ## $f1931
100 1# $aMunro, Alice, $d1931-

046 ## $f1899$g1961
100 1# $aHemingway, Ernest, $d1899-1961

046 ## $f1831?
100 1# $aSmith, James,$dborn 1831?
       [probable year of birth]

046 ## $f19360505
100 1# $aSmith, John,$d1936 May 5-

046 ## $o1977
110 2# $aDouble Image (Musical group : 1977-)

046 ## $o1989
110 2# $aDouble Image (Musical group : 1989-)

046 ## $o1925$p1979
100 3# $aPahlavi (Dynasty : 1925-1979)
       Please note that the family heading encoded in 
       100 3 has been constructed following RDA instructions 

2.4. Places

Discussion

RDA specifies data elements for various kinds of places associated with persons, corporate bodies, families, works, and expressions. The following are not defined in the MARC authority format and therefore need creating:

For a person:

• Place of birth is the town, city, province, state, and/or country in which a person was born (RDA 9.8.1.1)
• Place of death is the town, city, province, state, and/or country in which a person died (RDA 9.9.1.1)
• A country associated with the person is a country with which the person is identified. (RDA 9.10.1.1)
• Place of residence is the town, city, province, state, and/or country in which a person resides or has resided. (RDA 9.11.1.1)

For a corporate body:

• A place associated with the corporate body is a significant location associated with a corporate body (e.g., location of a conference, etc., location of the headquarters of an organization). (RDA 11.3.1.1)
  • A location of headquarters is a country, state, province, etc., or local place in which an organization has its headquarters. Alternatively, location of headquarters may indicate the geographic area (state, province, city, etc.) in which a corporate body carries out its activities (RDA 11.3.3.1). It is required when needed to distinguish a corporate body from another corporate body with the same name.

For a family:

• A place associated with the family is a place where the family resides or has resided or has some connection. (RDA 10.5.1.1). It is required when needed to distinguish a family from another family with the same name.

For a work:

• Place of origin of the work is the country or other territorial jurisdiction from which a work originated. (RDA 6.5.1.1). It is required when needed to differentiate a work from another work with the same title.

Place associated with conference, law, or treaty access points require further study and are not treated here.

This paper proposes the creation of field 370 (Associated place). It includes subfields allowing the recording of all the different types of places listed above. Subfield names have been generalised from the RDA element names so that they allow the recording of place information for a broad range of entities. For example, the country associated with a person can be recorded in subfield $c as per RDA instructions; this subfield may also be used to record the name of a country associated with a corporate body.

Data recorded in subfield $c (Associated country) can be encoded following RDA instructions (RDA 9.10.1.3). It may also include a country code, for example from the MARC code list for countries or from ISO 3166-1. Subfield $2 is available for recording the source of the controlled list used.

Field 370 also includes a subfield for date that may be associated with information in another subfield as some places associated with the entity described may vary over time. It may be associated with any subfields except $a and $b, as the dates for birth and death are recorded in new field 046. Field 370 should be repeated when dates in subfield $d are associated with a particular subfield (unless it applies to all subfields in the field), with the new field containing only the place subfield and its associated dates.

Proposed change

Define field 370 (Associated Place) (originally proposed as 621) as follows:

• 370 – ASSOCIATED PLACE (R)
  • Indicators
    • Both indicators are undefined; each contains a blank (#)
  • Subfield Codes
    • $a Place of birth (NR)
    • $b Place of death (NR)
    • $c Associated country (R)
    • $d Date associated with place (NR)
    • $e Place of residence/location of headquarters (R)
    • $f Other associated place (R)
    • $g Place of origin of work (R)
    • $2 Source (NR)
    • $6 Linkage (NR)
    • $8 Field link and sequence number (R)

Examples

100 1# $aSinger, Isaac Bashevis, $d1904-1991
370 ## $aRadzimyn, Poland$bSurfside, Fla.
        [born in Radzimyn, Poland; died in Surfside, Fla.]

100 1# $aOndaatje, Michael, $d1943-
370 ## $aColombo, Sri Lanka
370 ## $eEngland$d1954-1962
370 ## $cCanada$eCanada$d1962-
       [born in Colombo, Sri Lanka; lived in England from 
       1954-1962; moved to Canada in 1962]

100 1# $aHemingway, Ernest, $d1899-1961
370 ## $aOak Park, Ill.$bKetchum, Idaho$eOak Park, Ill.$eToronto, Ont.$eChicago, Ill.
       $eParis, France$eKey West, Fla.$eCuba$eKetchum, Idaho
       [born in Oak Park, Ill., died in Ketchum, Idaho; lived in Oak 
       Park, Ill.; Toronto, Ont.; Chicago, Ill.; Paris, France; Key West, Fla.; Cuba; 
       Ketchum, Idaho]

100 3# $aYan (Family)
370 ## $ePagsanjan, Philippines
       [family lived in Pagsanjan, Philippines]
       Please note that the family heading encoded in 100 3 has been 
       constructed following RDA instructions (which do not match current practice)

110 2# $aRepublican Party (Calif.)
370 ## $eCalif.

130 #0 $aAdvocate (Boise, Idaho)
370 ## $gBoise, Idaho
       [place of origin of the monthly Advocate]

130 #0 $aAdvocate (Nairobi, Kenya)
370 #0 $gNairobi, Kenya
       [place of origin of the monthly Advocate]

2.5. Address

Discussion

RDA includes an element for address, both for a person and a corporate body.

• Address of the person is the address of a person’s place of residence, business, or employer and/or an e-mail or Internet address. (RDA 9.12.1.1)
• Address of the corporate body is the address of the corporate body’s headquarters or offices, or an e-mail or Internet address for the body. (RDA 11.8.1.1)

This paper proposes the creation of field 371 (Address). For consistency with other MARC formats, this is modelled on field 270, which already exists in the MARC 21 bibliographic and community information formats. However, only the subfields that are useful for authority information have been defined in the Authority format. The indicators from the field 270 have also not been defined for field 371.

Subfield $t for date has been added as the address of a person or a corporate body may vary over time.

A subfield has not been added to field 371 for the Internet site of the entity in field 100 as field 856 was recently added to the Authority Format to enable recording of the Internet address.

During the MARBI meeting at Annual 2008, there were questions about how field 371 (Address) would relate to field 370 (Associated place). Field 370 (Associated place) includes information about places associated with a person, a corporate body, a family or a work at the level of the country, the town, etc. Address 371 (Address) is a refinement of the information contained in field 370; it contains information relating to the location of a person or a corporate body, at which they can be found or reached (e.g. printed mail address, e-mail address, etc.).

Proposed change

Define field 371 (Address) (R) (originally proposed as 622) as follows:

• 371 – ADDRESS (R)
  • Indicators
    • Both indicators are undefined; each contains a blank (#)
  • Subfield Codes
    • $a – Address (R)
    • $b – City (NR)
    • $c – Intermediate jurisdiction (NR)
    • $d – Country (NR)
    • $e – Postal code (NR)
    • $t – Date associated with address (NR)
    • $z – Public note (R)
    • $4 – Relator code (R)
    • $6 – Linkage (NR)
    • $8 – Field link and sequence number (R)

Examples

100 1# $aSmith, Arthur
371 1# $aBox 1216$bBarrière$cB.C.$dCanada$eV0E 1E0

110 2# $aCommunity Legal Education Ontario
371 1# $aSuite 600$a119 Spadina Avenue$bToronto$cON$dCanada$eM5V 2L1

2.6. Language

Discussion

RDA includes elements for language of a person and corporate body.

• Language of the person is the language a person uses when writing for publication, broadcasting, etc. (RDA 9.14.1.1)
• Language of the corporate body is a language a corporate body uses in its communications. (RDA 11.7.1.1)

Discussion Paper DP05/2 included two options: creating field 041 (Language code) in the authority format in parallel to the bibliographic format or creating a new field. The MARC Advisory Committee preferred defining a new field for language rather than reuse field 041, since language is defined differently in the authority format than it is in the bibliographic format.

This paper proposes the creation of Field 377 (Associated language). Subfield $a is repeatable to allow the recording of multiple languages associated with a person or a corporate body. Field 377 is repeatable to allow the recording of languages from different sources (e.g. MARC language codes, ISO639-3, etc.). Field 377 has been modelled on bibliographic field 041 for consistency. There was some discussion during the MARC Advisory Committee meeting at ALA Annual 2008 that it may be necessary to include a subfield for the term in addition to the code for the language in order to satisfy RDA requirements. Later clarification from the RDA Editorial team stated that this was not the case. It is suggested RDA implementers could generate the term from the code.

There was also some discussion about making provision for recording URIs for the language codes used. This issue is outstanding; it is dependent on the outcome of Discussion Paper 2009-DP01/1.

Proposed change

Define field 377 (Associated language) (originally proposed as 628) as follows:

• 377 – ASSOCIATED LANGUAGE (R)
  • Indicators
    • First indicator:
      • Undefined – contains a blank (#)
    • Second indicator – source of code
      • # – MARC language code
      • 7 – Source specified in subfield 2
  • Subfield Codes
    • $a – Language code (R)
    • $2 – Source of code (NR)
    • $6 – Linkage (NR)
    • $8 – Field link and sequence number (R)

Examples:

100 1# $aNabokov, Vladimir, $d1869-1922
377 ## $arus$aeng

110 2# $aCanadian Standards Association
377 ## $aeng$afre
377 #7 $aen$afr$2[code for iso639-1]

2.7. Activities

Discussion

RDA includes several elements related to activities of a person or corporate body. They include the following:

For a person:

• Field of activity of the person is a field of endeavour, area of expertise, etc., in which the person is engaged or was engaged (RDA 9.15.1.1)
• An affiliation is a group with which the person is affiliated or has been affiliated through employment, membership, cultural identity, etc. (RDA 9.13.1.1)
• Profession or occupation is a profession or occupation in which the person works or has worked. (9.16.1.1).

Both field of activity and profession or occupation are required for a person whose name consists of a phrase or appellation not conveying the idea of a person. For other persons, field of activity or profession or occupation are required when needed to distinguish a person from another person with the same name.

For a corporate body:

• Field of activity of the corporate body is a field of business in which the corporate body is engaged, its area of competence, responsibility, jurisdiction, etc. (RDA 11.9.1.1)

This paper proposes the creation of three separate fields, 372 for field of activity, 373 for affiliation, and 374 for occupation. The RDA/MARC Working Group considered creating the equivalent of bibliographic field 656 (Index term – Occupation) in the Authority format but decided this would not be appropriate. 656 is a subject access field, whose subfields do not seem to apply in this context. It was thought best to create a new field in the 37X block, where this paper is creating fields for most of the additional information about the entity described.

Each field includes subfield $2 so that if a controlled vocabulary is used, the source of the term used can be recorded.

A subfield for dates has also been included as the data recorded in those three fields may change over time. Subfield $a is repeatable and subfield $d is non repeatable as a person may have more than one field of activity/affiliation/profession or occupation at a time (similarly for field of activity of a corporate body). If these vary over time, the fields are repeated.

Proposed changes

Define field 372 (Field of activity) (originally proposed as 623) as follows:

• 372 – FIELD OF ACTIVITY (R)
  • Indicators
    • Both indicators are undefined; each contains a blank (#)
  • Subfield Codes
    • $a – Field of activity (R)
    • $d – Date(s) associated with field of activity (NR)
    • $2 – Source of term (NR)
    • $6 – Linkage (NR)
    • $8 – Field link and sequence number (R)

Define field 373 (Affiliation) (originally proposed as 624) as follows:

• 373 – AFFILIATION (R)
  • Indicators
    • Both indicators are undefined; each contains a blank (#)
  • Subfield Codes
    • $a – Affiliation (R)
    • $d – Date(s) associated with affiliation (NR)
    • $2 – Source of term (NR)
    • $6 – Linkage (NR)
    • $8 – Field link and sequence number (R)

Define field 374 (Occupation) (originally proposed as 625) as follows:

• 374 OCCUPATION (R)
  • Indicators
    • Both indicators are undefined; each contains a blank (#)
  • Subfield Codes
    • $a Occupation (R)
    • $d Date(s) associated with occupation (NR)
    • $2 Source of term (NR)
    • $6 Linkage (NR)
    • $8 Field link and sequence number (R)

Examples

100 1# $aHudson, David$cdidjeridu player
372 ## $adidjeridu player
        [field of activity included in 100 to differentiate from other Hudson, David]

100 1# $aAshton, John
373 ## $aFaculty of Biological Science, Leeds University$d2000-2005
373 ## $aFaculty of Life Sciences, Manchester University$d2005-
       [affiliation]

100 1# $aButler, Jean$ccomposer
374 ## $acomposer$2[code for controlled vocabulary]
       [occupation included in 100 to distinguish from another Jean Butler]

110 2# $aNorth Atlantic Treaty Organization
372 ## $aThe North Atlantic Treaty Organization (NATO) is a political and 
         military alliance of 26 countries from North America and Europe 
	 committed to fulfilling the goals of the North Atlantic Treaty signed 
	 on 4 April 1949.
        [Field of activity]

2.8. Gender

Discussion

RDA defines an element for gender of a person. Gender is the gender with which a person identifies (RDA 9.7). RDA instructs cataloguers to choose from the following list: female, male, unknown. If none of the terms listed is appropriate or sufficiently specific, record an appropriate term or phrase, e.g intersex.

This paper proposes the creation of field 375 for recording the gender of a person. Subfield 2 is included to allow for specifying the source of a controlled vocabulary (e.g. RDA list, ISO ISO/IEC 5218 “Information technology -- Codes for the representation of human sexes”).

Proposed change

Define field 375 (Gender) (originally proposed as 626) as follows:

• 375 – GENDER (R)
  • Indicators
    • Both indicators are undefined; each contains a blank (#)
  • Subfield Codes
    • $a – Gender (R)
    • $d – Dates associated with gender (NR)
    • $2 – Source of term (NR)
    • $6 – Linkage (NR)
    • $8 – Field link and sequence number (R)

Examples

100 1# $aNabokov, Vladimir, $d1869-1922
370 ## $amale$2[code for RDA list]

100 1# $aMorris, Jan,$d1926-
400 1# $wnne$aMorris, James,$d1926-
670 ## $a Author’s Conundrum, 1974
375 ## $amale$d1926-$2[code for RDA list]
375 ## $afemale$d1972?-$2[code for RDA list]
       [b. James Humphry Morris, Oct. 2, 1926; 
       had sex change operation, took new name "Jan Morris"]

2.9. Family names

Discussion

RDA includes elements for additional information about families that have not been recorded in separate elements previously. These include:

• Type of family is a categorization or generic descriptor for the type of family (RDA 10.3.1.1), e.g Family, Clan, Dynasty. Royal House.
• Prominent member of the family is a well-known individual who is a member of the family (RDA 10.6.1.1). It is required when needed to distinguish a family from another family with the same name.
• Hereditary title is a title of nobility, etc., associated with a family (RDA 10.7.1.1).

This paper proposes the definition of a single field, field 376, to include this additional information about the family. A subfield for date has been included since family membership can change over time.

Data recorded in subfield $b (Prominent member of the family) can be encoded following RDA instructions (10.6.1.3.), i.e. in the form of the preferred access point representing the person. It may also be encoded according to other description rules.

Please note that RDA instructs cataloguers to construct access points for families in a different way to current practice. The following examples illustrate RDA instructions.

Proposed change:

Define field 376 (Family Information) (originally proposed as 627) as follows:

• 376 – FAMILY INFORMATION (R)
  • Indicators
    • Both indicators are undefined; each contains a blank (#)
  • Subfield Codes
    • $a – Type of family (R)
    • $b – Name of prominent member (R)
    • $c – Hereditary title (R)
    • $d – Date associated with family information (NR)
    • $6 – Linkage (NR)
    • $8 – Field link and sequence number (R)

Examples

100 3# $aMedici (Royal house : Medici, Lorenzo de’, 1449-1492)
376 ## $aRoyal house$bMedici, Lorenzo de’, 1449-1492

046 ## $o1925$p1979
100 3# $aPahlavi (Dynasty : 1925-1979)
376 ## $aDynasty

100 3# $aCholmley (Family)
400 3# $aCholmeley (Family)
400 3# $aCholmondeley (Family)
376 ## $aFamily$cMarquesses of Cholmondeley
376 ## $aFamily$cDukes of Cholmondeley$d1852-

046 ## $o1529$p1739
100 3# $aNayak (Dynasty : 1529-1739 : Madurai, India) 
370 ## $fMadurai, India
376 ## $aDynasty

100 3# $aYan (Family : China)
370 ## $cChina
376 ## $aFamily

100 3# $aDenny (Family : Denny, Anthony, 1501-1549)
376 ## $aFamily$bDenny, Anthony, 1501-1549

100 3# $aDenny (Family : Denny, Arthur Amstrong, 1822-1899)
376 ## $aFamily$bDenny, Arthur Amstrong, 1822-1899
       [two families with the same name differentiated by 
       addition of prominent member of the family]

3. Summary of fields to be added to the authority format

• 046 – SPECIAL CODED DATES
• 370 – ASSOCIATED PLACE
• 371 – ADDRESS
• 372 – FIELD OF ACTIVITY
• 373 – AFFILIATION
• 374 – OCCUPATION
• 375 – GENDER
• 376 – FAMILY INFORMATION
• 377 – ASSOCIATED LANGUAGE

4. Appendix A: Extended Date Time Format

There is no standard date/time format that meets the needs of various well-known XML metadata schemas, for example MODS, METS, PREMIS, etc. ISO 8601 has multiple options for expressing date and time in a structured way, allowing the “basic” option without hyphens (YYYYMMDD plus minutes/seconds as appropriate) and the “extended” option with hyphens to separate the year from the month and the day (i.e. YYYY-MM-DD). A profile of ISO 8601 is available from the World Wide Web Consortium (W3C), which uses the extended form with hyphens (commonly known as “W3CDTF”). The form without hyphens has been used in a number of data elements in the MARC 21 formats (e.g. 005, 008) as well as in many databases. In addition there are special kinds of dates that are not covered by ISO 8601, so an extension is needed. The Extended Date Time Format (EDTF) is a definition that is both a profile of and an extension to ISO 8601.

EDTF is a profile because it would include relevant/necessary features of 8601 only, discarding unnecessary features and it would prescribe these features in a manner compatible with 8601. It is an extension because it would not, strictly speaking, be a profile of 8601, since it would include features that are not in 8601, thus extending it.

In EDTF the following list of known requirements was addressed:

• 01. The “basic” option in ISO 8601, i.e. YYYYMMDD without hyphens, and HHMMSS without colons.
• 02. BCE dates (covered by ISO 8601 and W3CDTF as an initial “-“ before the date). E.g. -0245.
• 03. Time zones (covered by ISO 8601 and W3CDTF as Z, or +hh:mm or –hh:mm).
• 04. Year and month only (i.e. no day of month), or year only. E.g. 1984-04 (Note that ISO 8601 requires that the hyphen be used between year and month when the day is left off in both the “basic” and “extended” formats.)
• 05. Questionable dates. E.g. 1992? would mean “possibly” the year 1992, but not “definitely”.
• 06. Approximate dates. E.g. 1992~ would mean “approximately” the year 1992.
• 07. Uncertain dates. E.g. 199? would mean some year in the 1990s, but not certain which year; 1999-?? would mean some month in 1999, 199901?? would mean some day in the month of 1999-01).
• 08. Date range (start and end).
• 09. Open end dates in a date range (“OPEN”).
• 10. Unknown date in a date range (Start and/or end date “UNKNOWN”).

See also http://www.loc.gov/standards/datetime/.