A local ArcGIS feature class is a named selection set of AutoCAD objects that share a common set of properties. You can create and configure them on the fly to display a particular subset of content as an ArcGIS-ready feature class that is recognized by ArcGIS Desktop. They function similarly to definition queries in ArcMap with the added ability to define attribute fields and attach feature attributes to native AutoCAD geometry.
| DWG objects | Description |
|---|---|
Dictionary | Dictionaries are nongraphic container objects that store custom data. They accept a variety of objects such as xrecords, data tables, and other dictionaries in nested form. |
Named object dictionary | The named object dictionary is the parent dictionary that owns all other dictionaries. It is an integral component of a DWG file and cannot be created or deleted. |
Extension dictionary | The extension dictionary is an object dictionary used to store and link arbitrary data to entities. The handle of the dictionary is stored in the definition of the object or entity. |
Xrecords | Xrecord objects are generic objects used to store nongraphic data by ObjectARX and AutoLISP applications. They are stored in object dictionaries or extension dictionaries with the DXF name XRECORD. The data comprises a DXF code type and a value. AutoLISP recognize them as lists expressed in dotted-pair notation. ObjectARX construct them as ResultBuffers. |
Linked-lists | A linked list is two or more ObjectARX Result Buffers or dotted-pair AutoLISP lists used to define an entity or object that contains a variety of properties and data types. For example, ((0 . "INSERT")(2 . "MyBlock")(8 . "MyLayer")). |
Selection filter | A selection filter is a linked list that defines selection criteria for creating a selection set object. In ObjectARX, the selection set is passed to a selection method. In AutoLISP, the selection set is passed to the get function. |
Caution:
Conditional operators are not currently supported by ArcGIS or the Teigha libraries. When creating selection set filter lists, use comma-delimited strings to create the OR condition for string-value properties such as layer names and line types.
The DWG object model diagram
