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The ISO Metadata Standards include identifiers for a large number if components. In 19115 these identifiers included a code and a citation for the authority of the code. This worked well in some cases, but it was difficult to simply associate a namespace with a code. In the revision the identifier has been expanded to include a namespace (called codespace), a version, and a description. This makes the identifiers easier to use in a web environment as well as making them easier for users to understand. Many NASA identifiers include short and long names. In the translation to ISO the short name becomes the code and the long name becomes the description.

Multiple metadata dates

ISO Metadata for NASA data and products is created, revised, and shared using several different systems.Tracking of metadata history and migration between Data Centers and Repositories is important for ensuring that users get current information. ISO 19115 includes the capability to define several types of dates and time ranges for resources, but only includes a creation date for the metadata. The creation date is important, but having the flexibility to define other dates types is also useful.  ISO 19115-1 includes seventeen date types (creation, publication, lastUpdate, nextUpdate, superseded, …) and any of them can be associated with the metadata. This is important for NASA because it allows more detailed tracking of metadata history and migration between Data Centers and Repositories. 

References to documentation or other information that is published in the literature

Information required for using and understanding NASA data and products comes in many forms. Structured and standard metadata can only include a portion of the documentation needed to use and understand many datasetsthis documentation. Other important information might published in user guides, data dictionaries , or scientific papers or other forms. ISO 19115-1 introduces the capability to add citations to that material those materials to the metadata record . The metadata record which becomes a discoverable source for links to all related documentation.

Data usage and limitations identified by users

NASA data are used in a variety of sometimes unexpected ways by diverse users all over the world. In some cases, those users identify limitations or usability problems. ISO 19115 includes information about when and how users are using data as well as limitations that they might identify as they use it. ISO 19115-1 introduces the capability for data providers to include responses to those limitations when they have been addressed. This is an important mechanism for understanding helping users understand how datasets are improved or updated in response to user their input.

Special constraints or use limitations for different time periods

Some datasets have special constraints for selected time periods. For example, some data can only be used by the principle investigator or members of the science team for some period of time after they are collected or their may be instrument problems that limit the utility of the data during some time period. Use of other data sets might be limited by license arrangements. ISO 19115-1 introduces the capability to specify temporal and spatial extents of constraints. It also allows the specification of specific constraints for particular users.

Do you need to describe coverages with physical measurements, quality information, auxiliary information, reference information, or model results?

Many NASA data and products are provided in grids and accompanied by gridded quality information or auxiliary data. ISO 19115 allows the description of multiple electromagnetic bands in coverages which can be useful for instrument data but difficult to use when datasets include coverages with multiple layers with different types of information. ISO 19115-1 extends the MD_Band object to include this capability. It includes simple descriptive statistics for each layer and allows inclusion of custom layer attributes as well.