This .NET class wraps the AcDbAttributeDefinition ObjectARX class. 

The AttributeDefinition class represents the ATTDEF entity within AutoCAD. ATTDEF entities are used within block definitions (BlockTableRecords) for AutoCAD to use as templates for creating ATTRIB entities (Attribute objects) when an INSERT (BlockReference) is created that references the block definition.

Autodesk.AutoCAD.DatabaseServices.DBObject
    Autodesk.AutoCAD.DatabaseServices.Entity
        Autodesk.AutoCAD.DatabaseServices.DBText
            Autodesk.AutoCAD.DatabaseServices.AttributeDefinition

Public Class AttributeDefinition
Inherits DBText

public class AttributeDefinition : DBText;

To set all the non-AttributeReference-specific properties such as position, text string, text height, text rotation, etc. for the attribute, use the methods inherited from Text.

DBObject, Entity, AttributeReference