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 over 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 which present the results in two ways:
Tables that include "Exists" in their titles give the average number of times that the metadata items (elements or attributes) occur per metadata record.
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.
Metadata serves an essential function in connecting users to people and organizations to help them access, use, and understand data. The ESDIS 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 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 completeness in the CMR (Elements)
Identifier completeness in the CMR (Items: Elements and Attributes)
Observations
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 can not 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 existence in the CMR (Elements)
Citation existence in the CMR (Items: Elements and Attributes)
Citation completeness in the CMR (Elements)
Citation completeness in the CMR (Items: Elements and Attributes)
Observations
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 existence in the CMR (Items: Elements and Attributes)
Online Resource completeness in the CMR (Elements)
Online Resource completeness in the CMR (Items: Elements and Attributes)
Observations
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 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 which 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
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 completeness in the CMR (Elements)
Date completeness in the CMR (Items: Elements and Attributes)
Observations
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 completeness in the CMR (Elements)
Keyword completeness in the CMR (Elements and Attributes)
Observations
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 completenss in the CMR (Elements and Attributes)
Observations