A DGN library is a DGN file used to store:

• Cells
• Levels
• Level filters
• Display styles
• Line styles
• Multi-line styles
• Text styles
• Dimension styles
• Detailing symbol styles
• Standards Checker settings
• Element templates
• Ribbon customizations
• Explorer link sets
• Print styles
• Customized tools, ribbon, toolboxes, and tasks

A DGN library, sometimes referred to as a DGNLib, contains data that is shared throughout files and among users. These shared resources consist of things that you define and name, which are used as standards by members of a workgroup.

The shared resources in a DGN library are created using the application tools, the same way they are created in a DGN file.

Each cell, level, and so on defined in a DGN library has a unique name that identifies it. When you use a cell, level, line style, multi-line style, text style, dimension style, or template from a DGN library, it is copied to your open DGN file and is given the same name. Each style, setting, and so on defined in a DGN library has a unique name that identifies it. When you use a style or template from a DGN library, it is copied to your open DGN file and is given the same name. This allows you to compare the local resource to the DGN library resource with the same name, to see if the contents of the DGN library have changed, to see if the local resource is out of sync with the DGN library resource, and to selectively apply updates to the local resource.

In addition to promoting the sharing of data and standards, DGN libraries provide other advantages:

• They provide structure, yet allow for exceptions when needed. You start with the resources from a DGN library, but they are not "locked" to prohibit you from changing them. You can make changes to the local resources as required by your customers.
• DGN libraries allow administrators to create shared resources in one place and to distribute them to many users. Having a central location for resources makes the maintenance and management of them easier.
• When you edit a DGN library you can use Undo and Redo controls from the Quick access toolbar.

If you are part of a small organization, you may want to store all of your resources in one DGN library, which is simpler and requires less administration. If you are part of a larger company with resources for different WorkSpaces and WorkSets, it makes sense to place them in multiple DGN libraries according to WorkSpaces and WorkSets.

A number of resources are stored in separate DGN libraries. This allows you to remove the DGN libraries that you do not need. The following DGN libraries are installed in ..\Default\dgnlib\ folder of MicroStation's program directory:

• ..\DrawComp\en\DrawingSeed.dgnlib — contains the default drawing seeds, display styles, and detailing symbol styles needed to create drawings.
• ..\DrawComp\en\PageLayout.dgnlib — contains the resources needed to create markup templates and the markup named expressions.
• ..\Links\LinkSetSeed.dgnlib — contains the default link set.
• ..\Printing\PrintStyles.dgnlib - contains the default print styles.
• ..\Render\LuxologyRender.dgnlib — contains the render settings and environment settings.
• ..\System\en\SystemCells.dgnlib - contains light cells, KML placemark cells, and the GPS tracking cells.

The following DGN libraries are installed to ..\Default\GUI\ folder of MicroStation's program directory:

• ..\en\GUI.dgnlib — contains the tasks, Main task, and context menus that are delivered with the product.
• ..\en\ifcicons.dgnlib — contains icons for displaying different types of ifc elements.
• ..\en\NamedExpressions.dgnlib — contains the delivered named expressions.
• ..\Explorer\en\Explorer.dgnlib — contains Explorer tree configuration and is not editable.

Multiple DGN libraries can be arranged in a hierarchy. The DGN libraries containing resources that are required at WorkSpace-level can be stored at WorkSpace-level. Similarly, DGN libraries containing resources that are required at WorkSet can be stored at WorkSets-level.

A DGN library has the same file format as a DGN file, except that it has a different file extension. The recommended file extension is *.dgnlib. The procedure for creating a DGN library, either by creating a new file from the beginning or by copying an existing file and saving it with a new name, is the same as for any DGN file.

When they are ready to be shared among users, DGN libraries should be moved to a central location to which everyone has at least read-only access.

The configuration variable MS_DGNLIBLIST specifies the list of DGN libraries that are available for use. For example, s:\standards\*.dgnlib. After DGN libraries are created, you need to set the configuration variable MS_DGNLIBLIST to point to the libraries in order to use them. Once this has been done, the shared resources stored in the DGN libraries will be available to you when you open a DGN file. For example, when you open the Element Templates dialog, all element templates in the configured DGN libraries appear in the list of element templates. There are some additional configuration variables that specify DGN libraries for specific styles. For example, MS_DGNLIBLIST_TEXTSTYLES specifies the list of DGN library files that are used to find text styles.

If the contents of a DGN library change, elements placed in DGN files prior to the change are not updated automatically in the open DGN file. You can synchronize your local resources with shared resources. This is done by using the Update from Library icon or menu item in each "style" dialog, or by using the following key-ins.

Digital rights and digital signatures can be applied to DGN libraries to protect their content and to sign approved shared resources. Design history can be used to track revisions of your standard shared resources.