During import, AutoCAD Map 3D toolset copies data from the input file into the active drawing and converts the data to drawing objects.
Connecting to Data Directly vs. Importing
You can work with your data using Data Connect or by importing it.
When you use Data Connect (from Display Manager), you view and edit data in its source. Edits are saved back to the source. The data stays in its original location.
When you import data, you make a copy of the data and bring that copy into your map. When you edit the data, you are editing the copy. The original data is unchanged.
For some formats, such as MicroStation Design (DGN), Arc/INFO, and SDF 2 (Autodesk MapGuide 6.5 and earlier), you can only import the data. For most other formats, you can either connect directly to the data or use import.