About Dragging Symbols and Surface Finishes
When you drag a symbol or surface finish away from the edge of an entity to which they are attached, an extension line is created. However, the extension line is created only if the symbol, surface finish, or an arrowhead of a leader is attached normal to any of the following entities.
Straight model edges (solid or surface)
Straight draft entities
Datum curves that are straight in 3D
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You cannot drag a symbol or surface finish away from an edge of an entity that is not straight.
When you drag the symbol or surface finish away from the edge of the entity, only the following placement types for a symbol, surface finish, and arrowhead of the leader support the creation of extension lines:
On Entity
Normal to Entity
With Leader (On Entity)
Tangent Leader (On Entity)
Normal Leader (On Entity)
If you have a surface finish from a non-straight model curve that appears straight in the drawing, you can drag the surface finish only up to the boundary of the curve.
You can modify the line style of extension lines by setting the leader_extension_font Detail option.