Metadata Source: CMR Metadata Collections

Metadata Dialect: ISO 19115-2

Commonly used documentation objects (CUDOS) such as Citations, ReponsibleParty and OnlineResource are key building blocks in the ISO 19115 standard.  These objects occur in many sections of the metadata model and are considered foundational to the standard. This page examines the usage of CUDOS in CMR metadata collections.

Metadata Collections

Overview

We examined more than 15,000 metadata records from 26 NASA and IDN collections extracted from the Common Metadata Repository (CMR) during April 2017. The links below connect to Tables that present the results in two ways:

1) Tables that include "Exists" in their titles give the average number of times that the metadata items (elements or attributes) occur per metadata record.

• Cells with numbers > 1.0 indicate elements that typically (although not necessarily) occur one or more times in each record in a collection.
• Cells with numbers = 1.0 indicate elements that typically occur once per record.
• Cells with number < 1 indicate elements that occur less than once per record and are, therfore, not included in all records in the collection. This value is typically the percentage of records in a collection that include the metadata element. 
• Cells with number = 0 and pink backgrounds indicate items that do not occur in any records in a collection.

2) Tables that include "Complete" in their titles give the % of records in a collection that include a metadata item. These values range from 0 (completely missing) to 1.0 (in all records) and do not provide information about how may times the item occurs.

Where are Contacts used in the CMR?

Metadata serves an essential function in connecting users to people and organizations to help them access, use, and understand data. The EOSDIS Common Metadata Repository (CMR) recognizes the importance of this type of information and includes two related elements in the Unified Metadata Model (UMM) Common Profile: Responsibility and Party. As elements in the Common Profile, these elements are included in all other UMM Profiles.

The Responsibility element broadly defines responsibilities related to data resources using the position of the element in the metadata model hierarchy. The UMM-Common Profile defines five responsibilities: Metadata Contact, Resource Author / Originator, Point of Contact, Distributor, and Processor. Each of these responsibilities can have multiple people or organizations (termed parties) associated with it. A RoleCode that is chosen from the standard ISO Codelist describes details of the roles of those parties. See Individuals, Organizations, and Roles for more information.

Click the links below to see how CMR metadata collections document contact information.  Select the tabs at the top of the sheet to see results for: Metadata Contact, Point of Contact, Resource Contact, Distributor Contact and Processor.

Contact Information Exists in the CMR (Items, Elements and Attributes)

Contact Information Complete in the CMR (Items, Elements and Attributes)

Observations

The list below identifies evaluation findings for Contact Information.

• The Metadata Contact organization exists in all CMR metadata collections and is complete in 22/26 collections
  
• The Point Of Contact organization exists in all CMR metadata collections and is complete is all collections with the exception of OMINRT
• Resource Contact information is missing from the majority of CMR metadata collections and is complete in 0 CMR collections
• Distributor Contact information is included in 20/26 of CMR metadata collections and is complete in 12 CMR collections
• NASA collections include only organization names for Processor Contact information. Ten collections include processor organization names but only 3 are complete. No processor information is included in any IDN collections.
• Email addresses are very sparsely populated for any type of responsibility in CMR metadata from DAACs and the IDN.

Where are Identifiers used in CMR metadata?

The need for identifiers in metadata records was first recognized in the DIF Standard and FGDC Remote Sensing Extensions. These standards introduced identifiers for the metadata records. In ISO 19115 this role is addressed by the fileIdentifier, a character string included in the MD_ or MI_Metadata object. This character string has been replaced with an MD_Identifier in  19115-1.

Including fileIdentifiers in the ISO metadata records gives metadata creators a mechanism for uniquely identifying them. This is becoming more important as metadata records evolve from single files into collections of related objects that can be harvested into repositories like geo.data.gov along multiple paths. There is no reliable way to identify duplicate records without a unique identifier in the actual record.

If the metadata records belongs to a parent metadata collection the parentIdentifier field can be used to reference the parent collection.

Identifiers are also used to reference resources associated with the data set or service described by the metadata. For example platforms, instruments, software, documentation, reports, partners and products can all be unambiguously referenced and described with the MD_Identifier object.

Click the links below to see where Identifiers are used in CMR metadata collections. Identifiers enable specific metadata concepts such platforms, instruments, Sensors, etc to be unambiguously identified. See Identifiers for more information.

Identifier existence in the CMR (Elements)

Identifier existence in the CMR (Items: Elements and Attributes)

Identifier (Elements Complete)

Identifier (Elements and Attributes Complete)

Observations

The list below identifies evaluation findings for Identifiers.

• Resource Identifier and File Identifier elements are complete in all CMR metadata collections
• Platform identifier exists in all CMR metadata collections and is complete in 22/26
• Instrument Identifier exists in all CMR metadata collections and is complete in 15/26 collections
• Reference System identifier exists in 25/26 CMR collections and is complete in 15/26 collections
• Operation identifiers exists in 22/26 CMR collections and is complete in 9/26 collections
• Sensor identifiers exists in 14 NASA metadata collections and is complete in 3 NASA collections
• Geographic Identifier exists in 7 NASA metadata collections and is complete in 1 NASA collection
• Aggregate Dataset Name Identifier exists in 9 CMR metadata collections and is complete in 0 CMR collections

Where are Citations used in CMR metadata?

Citations are used to provide information about citing the resource being described in the metadata or to refer to resources outside of the metadata record. These citations are an important part of the identification information and, as such, they are in a special location in the record. In addition, they can provide connection to relevant materials that cannot be included in the metadata.

Click the links below to see where Citations are used in CMR metadata collections. See Citations for more information.

Citation (Elements Exist)

Citation existence in the CMR (Items: Elements and Attributes)

Citation completeness in the CMR (Elements)

Citation (Elements and Attributes Complete)

Observations

The list below identifies evaluation findings for Citations.

• Resource Citation date and title elements are complete in all CMR  collections
  
• Instrument Citation exists in all CMR metadata collection and is complete in 15/26 CMR collections
• Contact Information for the Resource Citation is included in 3/26 CMR metadata collections and is complete in 0 CMR collections

Where are External Links (OnlineResources) used in CMR metadata?

As the World Wide Web has developed into a ubiquitous information source, links to on-line information and services have become a critical element in all metadata records. As URLs have increased in complexity, it has become more important to provide supporting information along with the links. The ISO Standards use CI_OnlineResources to describe links. These include a rich set of attributes for describing on-line resources.

Click the links below to see where Online Resource elements are used in CMR metadata collections.

Online Resource existence in the CMR (Elements)

Online Resource (Elements and Attributes Exist)

Online Resource completeness in the CMR (Elements)

Online Resource completeness in the CMR (Items: Elements and Attributes)

Observations

The list below identifies evaluation findings for Online Resources.

• An Online Resource URL for Distributor Transfer Options exists in all CMR metadata collections with the exception of OMINRT and is complete in 21 CMR collections
• An Online Resource URL for Keyword Thesaurus exists in 15/26 CMR metadata collections and is complete in 8 CMR collections
• An Online Resource URL for the Metadata Contact  and Point Of Contact exists in 17/26 CMR metadata collections and are complete in 2 or less CMR collections
• An Online Resource URL for Associated Resources exists in 7/26 CMR metadata collections and is complete in 0 CMR collections
• An Online Resource URL for Distributor Contact exists in 11/26 CMR metadata collections and is complete in 0 CMR collections
• An Online Resource URL for Processor Contact exists in 2 NASA metadata collections and is complete in 0 CMR collections
• An Online Resource description for Point Of Contact exists in 1 NASA metadata collections and is complete in 0 CMR collections

Where are Geographic Extents used in CMR metadata?

The EX_Extent object is used for describing geographic extents in ISO metadata.  The EX_Extent object provides several options for describing geographic extents; Bounding Box, Bounding Polygon, Geographic Desciptions and Spatial Temporal Extents.

Click the links below to see where geographic elements are used in CMR metadata collections.

Geographic Extent existence in the CMR (Elements)

Geographic Extent existence in the CMR (Items: Elements and Attributes)

Geographic Extent completeness in the CMR (Elements)

Geographic Extent completeness in the CMR (Items: Elements and Attributes)

Observations

The list below identifies evaluation findings for Geographic Extents.

• Bounding Box extent elements are used in all CMR metadata collection with the exception of OMINRT and are complete in 11/26 CMR collections
• 18 out of 26 CMR collection are using the extentTypeCode element with a value of '1'.  This field is complete in 6/26 CMR
• 8 NASA collections are using the gmd:geographicIdentifier/gmd:description.  Commonly recurring values include:

• • 'HORIZONTALTILENUMBER - Horizontal tile number of a grid, which increases from left to right'
  • 'VERTICALTILENUMBER - Vertical tile number of a grid, which increases from top to bottom'
  • 'TileID - MODIS Land tile identification number which represents a geographical area on the surface of the Earth bounded by latitude and longitude coordinates'
  • 'Universal Transverse Mercator (UTM)ZoneIdentifier'
• 7 NASA collections include a Geographic Identifier code with the most common value 'Universal Transverse Mercator (UTM)'

Where are Temporal Extents used in CMR metadata?

The EX_Extent object is used for describing temporal extents in ISO metadata.  In CMR metadata collections the gmi:TimePeriod element is most commonly used for describing temporal extents.  This TimePeriod element includes beginPositon and endPosition elements.  It's recommended that datasets that are ongoing use the indeterminatePosition='Now' attribute in the endPosition element.

Click the links below to see where temporal elements are used in CMR metadata collections.

Temporal Extent existence in the CMR (Elements)

Temporal Extent existence in the CMR (Items: Elements and Attributes)

Temporal Extent completeness in the CMR (Elements)

Temporal Extent completeness in the CMR (Items: Elements and Attributes)

Observations

The list below identifies evaluation findings for Temporal Extents.

• TimePeriod/beginPosition exists in all CMR collections and is complete in 22 CMR collections
• TimePeriod/end Position exists in 24/28 CMR collections and is complete in 2 CMR collections
• TimePeriod/endPosition exists in 7 CMR collections with an attribute value of indeterminatePosition='Now'.  This element is complete in 2 NASA collections.
• TimeInstant/timePosition exists in 1 CMR collection with an attribute value of framevalue='Eastern-Daylight'.

Where are Dates used in CMR metadata?

There are many dates included in the ISO Metadata Standards and they have several different types - each with its own characteristics.  The most common dates identified in CMR metadata collections include Metadata Creation/Revision date, Resource Citation date, Keyword Thesaurus date, Maintenance Update Frequency date, and Aggregation Information date. This Dates Wiki Page has information about valid formats for those dates.  Ron Lake's blog includes a helpful description of time in GML.

Click the links below to see the usage of  Date elements are used in CMR metadata collections.

Date existence in the CMR (Elements)

Date existence in the CMR (Items: Elements and Attributes)

Date (Elements Complete)

Date (Elements and Attributes Complete)

Observations

The list below identifies evaluation findings for Dates.

• Metadata Creation/Modified Date (timeStamp element) is complete in all CMR metadata collections
• Resource Citation Date is complete in all CMR collections
• Keyword Thesauraus Name Date exists in 15 NASA collections and is complete in 7 NASA collections
• AggregateDataSetName Date exists in 7 CMR metadata collections

How are Keywords used in CMR metadata?

Keywords are words or phrases that describe the metadata resource.  They facilitate search, indexing and discovery of metadata, and are the largest single component of many metadata collections, regardless of the dialect.

Click the links below to see how keyword elements are used in CMR metadata collections.

Keyword existence in the CMR (Elements)

Keyword existence in the CMR (Elements and Attributes)

Keyword (Elements Complete)

Keyword (Elements and Attributes Complete)

Observations

The list below identifies evaluation findings for Keywords.

• The Keyword element is complete in all CMR metadata collections
• The Keyword element is the most commonly used element in CMR metadata collections.

Where are Descriptions used in CMR metadata?

Descriptions are included in 14 ISO objects and are used for providing expanded free text documentation.  The Description fields most commonly used in CMR metadata collections are associated with Platforms  and Resource Citations.

Click the links below to see to see the usage of Description elements in CMR metadata collections.

Description existence in the CMR (Elements)

Description existence in the CMR (Elements and Attributes)

Description completeness in the CMR (Elements)

Description (Elements and Attributes Complete)

Observations

The list below identifies evaluation findings for Descriptions.

• The Platform description element exists in all 26 CMR metadata collections
• The Resource Citation description element exists in all NASA metadata collections and in 22/26 Other collections