A MicroStation document file is called a DGN file. A DGN file is composed of one or more models, each of which is represented using elements such as lines, arcs, and shapes. The File menu has items for creating, opening, and saving DGN files. These file management operations and others can also be performed using the File Open dialog.
You can have only one DGN file open at a time. If you open a DGN file when one is already open, the first file automatically closes.
You can, however, view the models contained in other DGN files by attaching them as references to the active model in the open DGN file.
When you create a DGN file, MicroStation copies one of the provided templates or seed DGN files. The seed file is copied to a new filename that you specify in the New dialog.
With the addition of the Set Seed File utility, MicroStation becomes more tightly integrated with Windows Explorer. Using this utility, you can specify the seed file that will be copied when you choose New > Bentley MicroStation Design File in Windows Explorer.
The MicroStation program group contains a shortcut to the Set Seed File utility.
The utility is a dialog that supports the following options for specifying the seed file:
prompt you to browse the file system
use the current seed file
use the seed file you selected in this dialog
Set Seed File utility dialog
By default, a thumbnail of the DGN file is created when the DGN file is saved. This thumbnail displays in the preview window on the File Open and Open dialogs. You can disable the creation of thumbnails by changing the MS_THUMBNAIL configuration variable to NONE (all uppercase).
If a DGN file has never been opened, the Bentley insignia displays in the preview window. If the DGN file has been saved but no thumbnail was created, the preview window is empty.
Set Seed File utility dialog
Ask me to pick the seed file each time
If selected, you are prompted to select a seed file when creating a new DGN file. If the Launch Window Explorer to show me the newly created file check box is enabled, the new DGN file automatically opens upon creation.
Use MicroStation's current seed file
If selected, the current seed file set in MicroStation is used when creating a new DGN file.
Use the seed file selected from this dialog (currently)
If selected, you navigate to the seed file to be used when creating a new DGN file from this dialog.
Compressing a DGN file reduces its size and clears the undo buffer.
The COMPRESS DESIGN key-in is used to compress files. This key-in automatically minimizes the number of levels that are in the level name dictionary (a list of all levels used in references, including nested references, in the master file). It also trims down the size of the reference attachment, view group, and saved view elements.
If you need to improve the performance of a DGN file, use the COMPRESS DESIGN INCLUDEREFS key-in. This key-in finds all references and nested references that are reachable from all models in the master file and compresses those files.
When you open a DGN file the product checks the size of the level name dictionaries in the file and its reference. If the number of entries in the level name dictionary exceeds the number of levels in the file by 2,000 or more, a warning appears in the Message Center. The warning tells you which DGN file contains a large level name dictionary and it advises you to use compressing. You can select File > Compress > Options, turn on the Include References check box in the Compress Options dialog and click OK, or run the COMPRESS DESIGN INCLUDEREFS key-in to compress the file and improve the performance. If the difference exceeds 10,000, a balloon text appears with the same warning message.
A level name dictionary stores the name of every level in the master file and the name of every level in each reference file that has ever been attached to any model within the file. A level name dictionary is an internal implementation and users cannot access it.
Unless you are recording the open DGN file's design history, compressing the file prevents previous changes from being undone.
To compress the open DGN file automatically when closing it, turn on Compress File on Exit in the Preferences dialog (Workspace > Preferences > Operation).
With regard to saving your work, MicroStation saves each change to the active model in the open DGN file — that is, your drawing — as it is made. You need only “manually” save changes to DGN file settings.
User preference settings are available to change MicroStation´s operation with regard to saving design changes and DGN file settings changes.
When you choose Save As from the File menu, you can save the open DGN file with a different name, in a different directory, on a different drive. MicroStation also closes the open DGN file and opens the newly saved DGN file.
BACKUP is a key-in.
You can specify a different default so that keying in BACKUP creates a backup copy in a different directory, on a different drive, or even on a drive connected to a different system on your network. Here are some examples:
Any part of a file specification included in a BACKUP key-in overrides the corresponding part of MS_BACKUP.
When working on models in an DGN file, you have the option of creating a design history for the DGN file. Typically, design history will have been initialized when the file was created by the system administrator, so there may be no need for you to initialize design history for a file.
With design history, you can track all of the changes to an DGN file by revision number, elements changed, revision type, and other parameters. When necessary, you can restore elements to a prior state through a combination of undoing and redoing historic changes. Changes also can be tracked down to the element level.
When you make changes to the design, you can commit them as a revision. How often you commit revisions depends on your personal preference or organizational requirements.
To help track the revisions, each is identified with a revision number, date and time, author, description of the change, and tags. When you commit a revision, it records the difference between the current state of the model and the last revision saved. The revisions appear in the Design History dialog.
DGN files created from a seed file with design history initialized will always have a design history.
The Merge utility is used to merge DGN files. Merging DGN files is essentially (but not entirely) the process of copying all models from one or more DGN files (the “source” file[s]) to another (the “destination” file).
You can review various DGN file properties in the Properties dialog (File > Properties) and change the Design Properties in the Summary tab. This tab contains text fields into which you can enter the following details:
Title — A title, as distinct from the filename in the file system.
Subject — A description of the file contents.
Client — The name of the client for whom the file was created.
Keywords — Keywords that can be used later in a database, for setting search criteria.
Comments — Comments regarding the file.
Manager — The name of the manager for the project.
Properties dialog, displaying the Summary tab
As well as being accessible from inside the product, much of the information in the Summary tab can be viewed in Windows Explorer, for example, by right-clicking the filename and selecting Properties.