The <Reference> field describes key bibliographic citations pertaining to the data set.

Bibliographic citations may be populated as a block of text in the free-text field or as text in subfields (see below). Citations in the free-text field may be provided in styles used by professional scientific journals such as the American Geophysical Union (AGU), American Psychological Association (APA), or Modern Language Association (MLA).


<Citation> Field to supply a block of text for the citation.

<Author> The name of the individual(s) or organization(s) with primary intellectual responsibility for the cited resources development. <Publication Date> The publication/reference date for the cited resource. If the Publication Date is not known, please use "Unknown".

<Title> The title (name) of the cited resource.

<Series> The name of a resource series, or aggregate (collection) resource of which the cited resource is a part.

<Edition> The version of a cited resource.

<Volume> The order or sequence of a resource in a series or set.

<Issue> The issue number of a resource (usually within a volume).

<Report_Number> The unique number or code assigned to a resource by the issuing organization(s).

<Publication_Place> The name of the city (and state or province and country if needed) where the resource was made available.

<Publisher> The name of the individual(s) or organization(s) that made the resource available.

<Pages> The range of pages or total number of pages of a cited resource.

<ISBN> International Standard Book Number.

<Persistent_Identifier> Set of sub-field describing a reference's persistent identifier.

<Type>The type of the Persistent Identifier, either DOI or ARK
<Identifier> The persistent identifier of the reference

<Online_Resource> The URL of the online resource containing the cited resource.

<Other_Reference_Details> Additional free-text reference information.



<Citation>Text </Citation>

<Author>Text up to 500 characters</Author>

<Publication Date>Text up to 31 characters, yyyy-mm-dd format suggested</Publication Date>

<Title>Text up to 220 characters</Title>

<Series>Text up to 220 characters</Series>

<Edition>Text up to 31 characters</Edition>

<Volume>Text up to 80 characters</Volume>

<Issue>Text up to 80 characters</Issue>

<Report_Number>Text up to 80 characters</Report_Number>

<Publication_Place>Text up to 80 characters</Publication_Place>

<Publisher>Text up to 500 characters</Publisher>

<Pages>Text up to 31 characters</Pages>

<ISBN>Text up to 220 characters</ISBN>


<Type>Persistent identifier keyword</Type>
<Identifier>Text up to 220 characters</Identifier>


<Online_Resource>Uniform Resource Locator (URL) up to 600 characters</Online_Resource>

<Other_Reference_Details>Text up to 220 characters</Other_Reference_Details>




Publication/reference is recommended and may be repeated. Subfields within publication/reference are not repeatable.

Persistent_Identifier/Type must either be DOI or ARK


Example using Citation subfield:


<Citation>Crum, T.D., and R.L. Alberty, 1993: The WSR-88D and the WSR-88D Operational Support Facility. Bull. Amer. Meteor. Soc., 74, 1669-1685.</Citation>


Example using subfields:


<Author>Tillis, G. M.</Author>


<Title>Measuring Taylor Slough boundary and internal flows, Everglades National Park, Florida</Title>

<Series>USGS Open-File Report</Series>


<Publication_Place>Tallahassee, FL</Publication_Place>

<Publisher>U.S. Geological Survey</Publisher>





This document should be cited as:
Directory Interchange Format (DIF) Writer's Guide, 2018.
Global Change Master Directory.
National Aeronautics and Space Administration.