Essential CAD vocabulary

The following table provides generic descriptions for equivalent AutoCAD and MicroStation terminology used in the help documentation. Some terms are in direct conflict with standard ArcGIS terms. For example, ArcGIS defines a layer as a cartographic representation of data, whereas AutoCAD defines it as a collection of entities or elements.




A user-defined graphic or nongraphic textual data element that may be linked to or embedded in another CAD object. Attributes and tag elements are often embedded in block or cell definitions to store field values.

Block reference


A user-defined collection of graphic elements and data treated as a single element or object, often used to symbolize point features.



A generic term used to describe a fundamental component object, usually with graphic representation, such as a point, a line, or text.



A collection of entities or elements of varied types and styles managed and visualized as a named stratum. It usually includes properties such as visibility and color and other visual characteristics.

Mapping Specification for CAD (MSC)

Esri's ArcGIS for AutoCAD plug-in software application and the ArcGIS Desktop Export to CAD geoprocessing tool create attributed ArcGIS feature classes in a DWG or DXF file.


A nongraphic data field element that serves as a primary key for linking a MicroStation graphic element to an external database. There is no equivalent mechanism in AutoCAD that is supported by ArcGIS.


Zero-length line

A nodal element used for locating a single coordinate location.


Element attributes

Data values that control specific visual characteristics of an entity or element such as visibility, color, and line style.



A named collection of properties used to classify and define specific geometric and textual elements such as a line style or text style.

Template file

Seed file

A drawing file used to store standard styles and common settings intended for reuse in other drawing files. This is used by the Export To CAD geoprocessing tool as an optional input parameter.


A nongraphic container object used to store data in a DWG file. Xrecords are similar to Xdata but are not limited by size or order. There is no equivalent mechanism in MicroStation.



An external drawing file attached to the current drawing file and often used for assembly or overlay purposes. It can also be a raster image in a supported file format.

Essential CAD vocabulary