A leader is an entity that consists of a polyline or spline, arrowhead at one end, and an annotation at the other end. The annotation can be an OdDbMText object, OdDbFcf object which is a Frame Control Feature (tolerance), or a block reference.

For more details, see the following topics:

Overview of Leaders

Specific Properties of Leaders

Working with Leader Lines

Working with Annotations of Leaders

Example of Working with Leaders

OdDbLeader Class in API Reference

A sample command for working with leaders is located in the Drawing\Examples\DevGuideCommands subdirectory of the ODA installation folder.