Classes

AcDbBasicFilter 

Filters objects (entities) in the current drawing based on layer, feature-class, and block criteria.
Filters are constructed with "*" as the default filtering value, indicating that all entities are to be filtered. Other valid values are "" (an empty string) to ignore entities during filtering, and NULL (a null filter) to exclude any entities returned by the filter set. The default AcDbBasicFilter object is constructed with * as the value for the Layers, FeatureClasses, and Blocks filtering criteria, and so will filter out classified blocks from all layers. The following table shows how to set entity-filtering criteria for various filtering... more 

AcDbObjectFilter 

Base class for creating filters that filter objects (entities) in the current drawing based on the specified criteria. Use this class to derive custom filters if you want to filter objects on criteria other than layers, feature classes, and blocks; otherwise, use the AcDbBasicFilterclass. Any class that you derive from this class must implement FilterObjects()to define the filtering criteria. To use multiple filters, use the AcDbObjectFilterGroupclass. 

AcDbObjectFilterGroup 

Filters objects (entities) in the current drawing based on the criteria of one or more listed filters. To create a filter, construct an instance of the AcDbBasicFilterclass or an instance of a class derived from the AcDbObjectFilterclass.