The ArcGIS metadata format
Metadata is part of an ArcGIS item. When the item is copied in ArcGIS, its metadata is also copied. When the item is imported into a geodatabase, its metadata is also imported. Metadata is stored in the same location as the item's data in a manner that is appropriate for its data type. For example, metadata is stored in the same location on disk as a shapefile's data in an accompanying XML file. For geodatabase items, metadata is stored in the geodatabase system tables. If your data is stored in an enterprise geodatabase, see the topic that describes the geodatabase system tables for your DBMS to learn more; metadata is stored in the Documentation column in the GDB_Items table.
ArcGIS provides access to metadata for all items as an XML document, regardless of how it is physically stored. The ArcGIS metadata editor reads and stores information in a specific set of XML elements in that document. Collectively, these elements are referred to as the ArcGIS metadata format.
The current version of ArcGIS is designed to create, maintain, and use information stored in the ArcGIS metadata format.
The ArcGIS metadata format contains elements that can store all content in all metadata standards that are supported by ArcGIS Desktop. It includes all FGDC metadata content, all ISO 19139 metadata content, all North American Profile metadata content, and all INSPIRE metadata content. It also includes ArcGIS-internal content such as thumbnails, enclosures, and detailed properties of ArcGIS items; this information is useful, but is not included in official metadata standards and profiles.
No matter which metadata standard or profile you are following, you enter content with one editor—the ArcGIS metadata editor. No matter which metadata style you use, all information that you provide in the Description tab is stored in the same manner in the item's metadata—in the ArcGIS metadata format. By default, when you view an item's metadata, ArcGIS automatically records information about its intrinsic properties in its metadata in a process known as synchronization; these properties are only stored and updated in the ArcGIS metadata format.
Choosing a metadata style is like applying a filter to ArcGIS metadata. The ArcGIS metadata editor and the underlying ArcGIS metadata format remain the same, but the new filter changes your metadata experience. It can alter how much metadata content is viewed and how it is displayed, and which pages are included in the editor and how they work. For metadata styles designed to support a standard or profile, the filter ensures you are working with content that is appropriate for that standard or profile as well as information that is important in ArcGIS, such as thumbnails and field descriptions. While different styles might give you access to more or less metadata content, that information is always ArcGIS metadata.
If you are creating FGDC-style metadata today, and a year from now your organization decides to create North American Profile-style metadata instead, that's OK. To make that change you only need to change your metadata style in ArcGIS. When you change your metadata style, all of the content you entered before is still exactly the way you left it because metadata content is stored the same way for all metadata styles. You might be required to provide some different information than before to comply with the new standard's rules, but you don't need to change anything else.
ArcGIS metadata XML elements
For new items created with the current version of ArcGIS, if you view and edit their metadata in the Description tab, that metadata will only contain information stored in the ArcGIS metadata format. However, if an item has existed for some time, its metadata likely has content that was created using ArcGIS Desktop 9.3.1 or an earlier release. Its metadata content is likely stored in either the FGDC or ESRI-ISO metadata XML formats alongside other ArcGIS-internal information.
The 9.3.1 FGDC metadata editor and utilities created, displayed, and managed content in the native FGDC metadata XML format inside an item's metadata. The 9.3.1 wizard-style ISO metadata editor and utilities created, displayed, and managed content in the ESRI-ISO XML format. The FGDC format XML elements and the ESRI-ISO format XML elements are mutually exclusive. If both metadata editors were used, an item's metadata would contain two copies of the same information in parallel sets of XML elements. Supporting other standards involved adding custom editors and utilities for creating, displaying, and managing content; these would typically manage content in additional sets of parallel XML elements.
The ArcGIS metadata format borrows a few XML elements from the FGDC XML format—the elements that describe an item's attributes. It also borrows many XML elements included in the ESRI-ISO XML format; in some respects you can think of the ArcGIS metadata format as version two of the ESRI-ISO format. However, ArcGIS metadata also includes many new XML elements, as well, and stores some of the same information in a new way.
When you view metadata for existing items, new synchronized ArcGIS metadata elements will automatically be added alongside any existing FGDC-formatted or ESRI-ISO-formatted metadata content.
When you use any metadata style that supports viewing an item's complete metadata, you can see all content stored in the ArcGIS metadata format under the ArcGIS Metadata heading. If the item's metadata includes content stored in the ESRI-ISO metadata format, it will be upgraded automatically when you view the metadata. Therefore, you'll see this content under the ArcGIS Metadata heading as ArcGIS metadata. Upgrading existing ESRI-ISO metadata is discussed further below.
You can also see any content stored in the FGDC metadata format under the FGDC Metadata (read-only) heading; this heading only appears if FGDC-formatted metadata exists. Content that is shared between the FGDC format and the ArcGIS metadata format will appear under both headings.
While you can see FGDC-formatted content, this information is only available for viewing in the Description tab, which is why the information is identified as being read-only.
Upgrading to ArcGIS metadata
If an item has existing metadata content that is not in the ArcGIS metadata format, the current version of ArcGIS Desktop can't use that information. For example, the ArcGIS metadata editor and the Export and Validate buttons only work with content that is stored in the ArcGIS metadata format. When you use the Import button, the metadata content you are importing is converted to the ArcGIS metadata format.
There is no need to retype all of an item's existing metadata in the Description tab. A geoprocessing tool is available to upgrade existing FGDC-formatted metadata content or ESRI-ISO-formatted metadata content to the ArcGIS metadata format.
The Upgrade Metadata tool copies information in existing FGDC or ESRI-ISO metadata elements that are not included in the ArcGIS metadata format to the equivalent ArcGIS metadata elements. Upgrading doesn't alter the item's ArcGIS-internal content: the geoprocessing history, thumbnail, enclosures, and so on. Upgrading doesn't remove any existing FGDC- and ESRI-ISO-format elements. Properties of the item that were recorded in its metadata by ArcGIS Desktop 9.3.1 aren't upgraded. The current version of ArcGIS automatically updates the item's metadata to include its current properties at the end of the upgrade process.
After upgrading, your original metadata content is available in the Description tab for editing, validating, exporting, and other operations in ArcGIS. If you have been creating metadata following the FGDC CSDGM metadata rules and guidelines, the arrangement and names of elements will be a bit different than you are accustomed to in the ArcGIS metadata editor, but all of the FGDC metadata concepts are available in the Description tab.
If an item has existing metadata in the ESRI-ISO format that was typed by a person—not automatically added by ArcGIS 9.3.1—it is upgraded automatically to ArcGIS metadata when you view it in the Description tab. The automatic upgrade is not permanent; it is discarded unless you edit the item's metadata and save your changes in the Description tab.
In contrast, existing FGDC-format metadata is not upgraded automatically. You will be notified that your existing FGDC-format metadata must be upgraded to the ArcGIS metadata format before it can be used in the Description tab when all of the following are true:
- Some of the item's FGDC-format metadata content was typed into a metadata editor—not added automatically by ArcGIS Desktop 9.3.1.
- No content was typed into a metadata editor that stored information in the ESRI-ISO metadata format—content added automatically by ArcGIS Desktop 9.3.1 in this format is ignored.
- No metadata was typed into the Description tab and saved anywhere except the Item Description page.
Click Yes to upgrade the existing FGDC metadata content right away. The Upgrade Metadata tool opens and the Upgrade Type is automatically set to FGDC_TO_ARCGIS. If you would rather wait, click No. The Upgrade button will be available in the Description tab. You can use it later to upgrade the item's metadata. If you prefer not to be notified when existing FGDC metadata content hasn't been upgraded, check the option Do not show this message in the future. Notifications can be enabled again in the Options dialog box for your ArcGIS Desktop application.
If an item's metadata includes existing content typed by a person in both the FGDC and ESRI-ISO metadata elements, you must choose one set of information to upgrade to ArcGIS metadata. You should upgrade whichever set of metadata is more complete to ensure you don't lose important information. Usually, the FGDC metadata content will be more complete.
If you prefer to upgrade metadata for many items at once instead of one at a time, run the Upgrade Metadata tool in batch mode or with a Python script using the appropriate upgrade type. For example, you might upgrade metadata for all items in a folder or geodatabase.
More about FGDC metadata
If you edit metadata using the FGDC metadata editor add-in, it adds and edits content in the native FGDC metadata XML format inside an item's metadata. This content is displayed under the FGDC Metadata (read-only) heading.
Upgrading existing FGDC metadata content is strongly recommended to support basic operations in the current version of ArcGIS Desktop that involve metadata.
If you don't upgrade, you can search for items in ArcGIS, and publish them to ArcGIS Online. When information isn't found in the ArcGIS metadata elements associated with the Item Description metadata style, ArcGIS will look for information in the related FGDC metadata elements and index or publish that content instead. In the same manner, you can view an item's simple Item Description summary. However, the rest of the item's FGDC metadata content remains unavailable. Most of the existing content won't appear under the ArcGIS Metadata heading. The buttons in the Description tab won't process any FGDC-format metadata. ArcGIS won't automatically update it with the item's current properties. Other operations in ArcGIS may not find the information they are looking for and require you to retype some information.
If the item's existing FGDC metadata hasn't been upgraded, and you start editing metadata in the Description tab, the Item Description page displays the same content as the simple Item Description display and the Field page shows the existing FGDC attribute descriptions. The other pages will be empty except for any synchronized properties that you can edit. If you edit information on the Item Description page, your edits are saved in both the FGDC metadata elements and the corresponding ArcGIS metadata elements. If you edit information on the Fields page, your edits are saved in the FGDC metadata elements, which are shared with ArcGIS metadata. If you add content using any other page, your changes are saved to the appropriate ArcGIS metadata elements only.
Once an item's metadata includes ArcGIS metadata content that was upgraded or typed by a person, any future indexing and publishing operations only use information stored in the ArcGIS metadata format. Also, the simple Item Description display and the Item Description page in the ArcGIS metadata editor will only show and update ArcGIS metadata elements—the associated FGDC metadata elements will no longer be updated.
When FGDC metadata is upgraded to ArcGIS metadata, a copy of the item's original metadata document is stored within the item's metadata as an enclosure for reference. You can access it using the Metadata Properties button on the ArcCatalog Metadata toolbar.