Introduction
This wiki resource provides best practices documentation for all collection and granule metadata concepts supported by the Common Metadata Repository (CMR). It is intended to support metadata authors as well as provide general guidance to those seeking information about CMR supported metadata.
The wiki is organized by metadata concept as specified in the Unified Metadata Model (UMM) and includes information such as: required metadata fields, definitions for each metadata concept, best practices for populating each metadata field, guidance on how to use controlled vocabularies, and the revision history of the UMM metadata schema. Also included are a detailed mapping/crosswalk between each UMM metadata field and the corresponding field in each CMR supported metadata standard. Supported standards currently include ECHO 10, DIF 10, and ISO 19115-2 (in NASA specific MENDS and SMAP "flavors"). Click here to jump directly to the documentation.
Unified Metadata Model (UMM)
The UMM is used as a bridge to map between each of the CMR-supported metadata standards. A number of different objects require descriptive metadata that is modeled using a corresponding UMM profile. For example, a collection (or dataset level) object is modeled using the UMM-C (Collection) profile, and granule (or file level) objects are modeled using the UMM-G (Granule) profile.
While UMM-C and UMM-G are separate entities, some elements are common to each profile and are therefore modeled using UMM-Common.
Currently, this wiki resource provides documentation for elements found in the UMM-C, UMM-G and UMM-Common models.
Other UMM models not covered here include UMM-S (Services), UMM-T (Tools) and UMM-Var (Variables).
For information regarding UMM-S, please refer to the CMR Documents page and the UMM-S Curator's Guide.
For information regarding UMM-T, please refer to the CMR Documents page. Information on how to generate UMM-T records can be found in the MMT User's Guide.
For information regarding UMM-Var, please download the UMM-Var document from the CMR Documents page. Information on how to generate UMM-Var records can be found in the MMT User's Guide and the UMM-Var Generator (UVG) User's Guide.
Wiki Page Structure
Each wiki page is structured as follows:
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Element Description - Provides a high-level definition of the metadata concept
Best Practices - Provides best practices for the metadata concept as well as example values
Element Specification - A table detailing each unique metadata element within the concept. For each metadata element, the table specifies:
- The UMM model it is from (UMM-Common, C, or G)
- The element name exactly as it appears in the UMM schema
- The element type (string, decimal, enumeration, boolean, etc.)
- Constraints (e.g. character length restrictions, controlled vocabularies, etc.)
- The cardinality, which specifies how many times the element may be repeated
- Notes: Any additional information which may be useful about the element
Metadata Validation and QA/QC - There are various systems in place to ensure a certain standard of metadata quality is maintained in the CMR. The Metadata Validation and QA/QC section of the wiki page provides documentation regarding these efforts and systems:
- GCMD Metadata QA/QC: The GCMD team is responsible for the stewardship of metadata records in the CMR provided by any of CMR's International Directory Network (IDN) partners. This section details both the automated and manual checks the GCMD team performs on the IDN records to help maintain a certain standard of quality.
- CMR Validation: The CMR system itself has certain requirements. This section details any baseline CMR requirements for the metadata concept.
- ARC Metadata QA/QC: The ARC team is responsible for performing quality assessments of NASA metadata records in the CMR. This section specifies what the ARC team looks for (both manually and in an automated fashion) to ensure NASA's metadata records in the CMR maintain a certain standard of quality.
Dialect Mappings - The Dialect Mapping section provides detailed element-element mappings between the UMM and each CMR supported metadata standard. Current CMR supported metadata standards for collection-level metadata include:
- UMM-JSON (UMM-C/Common)
- DIF 10
- ECHO 10
- ISO 19115-2 MENDS
- ISO 19115-2 SMAP
- CMR supported metadata standards for granule-level metadata include:
- UMM-JSON (UMM-G)
- ECHO 10
- ISO 19115-2 MENDS
- ISO 19115-2 SMAP
- Provided for each supported standard:
- An element specification table that includes the direct crosswalk between the UMM element path and the corresponding element path in the supported standard. This table will also indicate if an element in a supported standard does not map to the UMM, or if there are any caveats in the manner that the information gets translated.
- An enumeration mapping table (if applicable) - sometimes there are differences in enumeration values used in a supported standard versus the UMM. These differences are identified in the enumeration mapping table.
- An example mapping showing how a snippet of metadata in the supported standard will appear in the UMM format. This may illustrate examples of how certain information can get dropped or only partially translated between the supported standard and the UMM.
UMM Migration - If a metadata concept undergoes significant changes between UMM version updates, this section will illustrate how the information provided in the older UMM version gets translated to the newer version
History - Provides a version history for the metadata element
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Documentation Directory
There is a separate wiki page for each high-level metadata concept in the UMM. Click on the expandable tables below to view a listing of available metadata concepts and access the documentation for each concept:
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| title | Data Identification Concepts |
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| Element | UMM Model | Definition | Required |
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| Abstract | UMM-C | This element provides a brief description of the dataset the metadata represents. | Yes | | Access Constraints | UMM-C | This element describes any restrictions imposed on data access. Access Constraints can be described in a free text field with the option to provide an access control list (ACL) value. | No | | Archive and Distribution Information | UMM-C | This element and all of its sub-elements allow a data provider to provide archive and distribution file information upfront to an end user to help them decide if they can use the product. The file information includes AverageFileSize - typically used for granules as well as file formats and other file information. | No | | Direct Distribution Information | UMM-C | The direct distribution information main element allows data providers to provide users information on getting direct access to data products that are stored in the Amazon Web Service (AWS) S3 buckets when they are initially looking at a collection. The end users get information such as the S3 credentials end point, a credential documentation URL, as well as bucket prefix names, and an AWS region. | No | | Collection Citation | UMM-C | This element provides the information required to properly cite the collection in professional scientific literature. | No | | Collection Data Type | UMM-C | This element is used to identify the collection as a Science Quality Collection or as a non-science-quality collection such as a Near Real Time collection. | No | | Collection Progress | UMM-C | This element describes the production status of the dataset. | Yes | | Contact Group | UMM-Common | This element is used to provide contact information for a group associated with the dataset. | No | | Contact Person | UMM-Common | This element is used to provide contact information for an individual associated with the dataset. | No | Data Center | UMM-Common | This element is used to identify and provide contact information for the organization responsible for originating, processing, archiving, and/or distributing the dataset being described in the metadata. | Yes | | Data Dates | UMM-C | This element is used to identify dates when the data or resource itself changed in some way. | No | | Data Language | UMM-C | This element describes the language used in the preparation, storage, and description of the collection. It is the language of the collection data itself. It does not refer to the language used in the metadata record (although this may be the same language) | No | | DOI | UMM-C | This element stores the DOI (Digital Object Identifier) that identifies the dataset. | Yes, if applicable | | Associated DOIs | UMM-C | This element stores the DOIs (Digital Object Identifier) for associated collections or other associated items. | No | | Entry Title | UMM-C | This element describes the title of the dataset described by the metadata.
| Yes | | Maturity | UMM-C | This element describes the collection life cycle. There are four valid values: Beta refers to collections that intend to enable users to gain familiarity with the collections parameters and data formats. Provisional collections allow users to find the data and process studies where the product doesn't need rigorous validation or top quality. Validated products are high quality data that have been fully validated. Deprecated products have been retired but are still discoverable for historical purposes. | No | | Metadata Association | UMM-C | This element is used to identify other metadata resources that are dependent on or related to the data described by the metadata. | No | | Processing Level | UMM-C | This element describes an identifier indicating the level at which the data in the collection are processed, ranging from level 0 (raw instrument data at full resolution) to level 4 (model output or analysis results). | Yes | | Publication Reference | UMM-C | This element describes key bibliographic citations pertaining to the collection. | No | | Purpose | UMM-C | This element contains suggested usage for the data and/or a description of why the resource exists. | No | Quality | UMM-C | This element describes the quality of the dataset. | No | | Short Name | UMM-C | This element describes the dataset short name. | Yes | | Use Constraints | UMM-C | This element defines how data may or may not be used to assure the protection of privacy or intellectual property. This includes license information as well as any special restrictions, legal prerequisites, terms and conditions, and/or limitations on using the dataset. | No | | Version | UMM-C | This element describes the dataset version. | Yes | | Version Description | UMM-C | This element describes the version of the dataset. | No |
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| title | Temporal Information Concepts |
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| Element | UMM Model | Definition | Required? |
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| Paleo Temporal Coverage | UMM-C | This element defines the time period for geologic and/or paleoclimate data. The element is predominantly used for data samples that originated prior to 01-01-0001. | No | | Temporal Extent | UMM-Common | This element describes when data were acquired or collected. | Yes | | Temporal Keywords | UMM-C | This element specifies a word or phrase which serves to summarize the temporal characteristics of a dataset. | No |
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| title | Spatial Information Concepts |
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| Element | UMM Model | Definition | Required? |
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| Location Keywords | UMM-C | This element contains keywords that characterize the study area/region where data was collected. | No | | Spatial Extent | UMM-Common | This element describes the geographic coverage of the data. | Yes | | Spatial Information | UMM-C | This element stores information about the reference frame from which horizontal and vertical spatial domains are measured. The horizontal reference frame includes fields for Geodetic Model, Geographic Coordinates, and Local Coordinates. The Vertical reference frame includes fields for altitudes (elevations) and depths. | No | | Tiling Identification System | UMM-Common | This element defines a named two-dimensional tiling system related to the collection. | No |
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| title | Acquisition Information Concepts |
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| Element | UMM Model | Definition | Required? |
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| Platform | UMM-Common | This element describes the relevant platforms used to acquire the data. | Yes | | Instrument | UMM-Common | This element is used to register the device that measured or recorded the data, including direct human observation. | No | | Project | UMM-Common | This element describes the scientific endeavor(s) with which the collection is associated. | No |
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| Element | UMM Model | Definition | Required? |
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Related URL | UMM-Common | This element describes any resource-related URLs that include project home pages, resource information pages, services, related data, archives/servers, metadata extensions, direct links to online software packages, web mapping services, links to images, documents, or other data. | Yes | | Online Resource |
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| title | Descriptive Keyword Concepts |
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| Element | UMM Model | Definition | Required? |
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| Additional Attributes | UMM-C | This element stores the data's distinctive attributes (i.e. attributes used to describe the unique characteristics of the resource which extend beyond those defined in this mapping). | No | | Ancillary Keywords | UMM-C | This element allows metadata authors to provide words or phrases beyond the controlled Science Keyword vocabulary to further describe the collection. | No | | ISO Topic Category | UMM-C | This element identifies the topic category (or categories) from the EN ISO 19115 Topic Category Code List that pertain to a collection. | No | | Science Keywords | UMM-C | This element enables the specification of Earth Science keywords. | Yes |
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| title | Metadata Information Concepts |
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| Element | UMM Model | Definition | Required? |
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| Directory Names | UMM-C | This element has been used historically by the GCMD internally to identify association, responsibility and/or ownership of the dataset, service, or supplemental information. Note: This field only occurs in the DIF. When a DIF record is retrieved in the ECHO10 or ISO 19115 formats, this element will not be translated. | No | | Metadata Dates | UMM-C | This element is used to identify dates when the metadata changed in some way. This element is made of two sub-elements, Type and Date. | No | | Metadata Language | UMM-C | This element specifies the language used in the metadata record (i.e. English, French, Chinese, etc.). | No |
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| title | Granule Specific Concepts |
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| Element | UMM Model | Definition | Required? |
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| Archive and Distribution Information for Granules | UMM-G | This element provides information about the files or file packages that make up the granule. | No | | Cloud Cover | UMM-G | This element describes a percentage value indicating how much of the area of a granule (the EOSDIS data unit) has been obscured by clouds. It is worth noting that there are many different measures of cloud cover within the EOSDIS data holdings and that the cloud cover parameter that is represented in the archive is dataset-specific. | No | | Collection Reference | UMM-G | This element describes the collection metadata record's short name and version or entry title to which this granule metadata record belongs. | Yes | | Day Night Flag | UMM-G | This element identifies whether a granule was collected during the day, at night (any time between sunset and sunrise), or both. | No | | GranuleUR | UMM-G | This element describes the Universal Reference ID of the granule referred by the data provider. This ID is unique per data provider. | Yes | | Grid Mapping Names | UMM-G | Represents the native grid mapping of the granule if the granule is gridded. | No | | Identifiers | UMM-G | This element holds various types of granule identifiers. | Yes | | Input Granules | UMM-G | This element describes the identification of the input granule(s) for a specific granule. | No | | Measured Parameters | UMM-G | This element describes the name of the geophysical parameter expressed in the data as well as associated quality flags and quality statistics. The quality statistics element contains measures of quality for the granule. The parameters used to set these measures are not preset and will be determined by the data producer. Each set of measures can occur many times either for the granule as a whole or for individual parameters. The quality flags contain the science, operational and automatic quality flags that indicate the overall quality assurance levels of specific parameter values within a granule. | No | | Metadata Specification | UMM-G | Requires the user to add schema information into every granule record. It includes the schema's name, version, and URL location. The information is controlled through enumerations at the end of this schema. | Yes | | Native Projection Names | UMM-G | Represents the native projection of the granule if the granule has a native projection. | No | PGE Version Class | UMM-G | This element describes basic descriptive characteristics related to the Product Generation Executable associated with a granule. | No | | Production Date Time | UMM-G | This element provides the exact date and time a granule was produced using the following format: YYYYMMDDTHH:MM:SS (time is in UTC). | Yes | | Provider Dates | UMM-G | This element describes the dates related to activities involving the granule and the data provider database with the exception of Delete. For Create, Update, and Insert, the date is the date that the granule file is created, updated, or inserted into the provider database by the provider. Delete is the date that the CMR should delete the granule metadata record from its repository. | Yes | Related URLs (Granules) | UMM-G | *Will probably combine with existing Related URLs UMM-Common page | Yes | | Reprocessing Actual | UMM-G | This element provides what, if any, reprocessing has been performed on a granule. | No | | Reprocessing Planned | UMM-G | This element provides what, if any, reprocessing may be performed on a granule. | No | Spatial Extent | UMM-G | This element contains attributes that describe the horizontal (geographical) and/or vertical region over which the data was acquired. Spatial Extent includes any or all of Granule Localities, Horizontal Spatial Domain, and Vertical Spatial Domain. | No |
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Click here to see a list of all Collection level (UMM-C) metadata elements and corresponding documentation.
Click here to see list of all Granule level (UMM-G) metadata elements and corresponding documentation.
Additionally, there are some metadata concepts in CMR supported metadata standards that are not included in the UMM. Please refer to this wiki page for a list of ECHO 10 and DIF 10 metadata elements that do not translate to the UMM.
Additional Resources
Below are additional resources regarding the UMM and the CMR:
Unified Metadata Model:
Miscellaneous CMR Resources:
