About the Extend User Interface
The Extend user interface consists of:
• The feature icon
• The Extend tab
• The tabs on the Extend tab
The Feature Icon
The Extend tool is identified by 
on the Import DataDoctor ribbon tab. To access the Extend tool, select the boundary edge of a surface and click > Extend on the Import DataDoctor tab.
on the Import DataDoctor ribbon tab. To access the Extend tool, select the boundary edge of a surface and click > Extend on the Import DataDoctor tab.The Extend Tab
The Extend tab consists of:
• 
Along Surface—Extends the surface along the original surface.
Along Surface—Extends the surface along the original surface.• The Dimension Box—You can specify the distance for the surface extension. Enter a new value or select a value from the list.
• 
To Plane—Extends the surface to the selected reference plane.
To Plane—Extends the surface to the selected reference plane.• The Plane collector—Lets you add or remove a reference datum plane.
• 
—Flips the direction of the extension surface relative to the selected boundary edge chain. Not available for the extension of a variable surface.
—Flips the direction of the extension surface relative to the selected boundary edge chain. Not available for the extension of a variable surface.Tabs within the Extend Tab
The Extend tab contains the following tabs:
• The References tab
◦ Boundary edge—Lets you change the edge or chain reference.
◦ Details—Displays the Chain dialog box and enables you to review and edit the chain properties.
◦ Reference plane—Enables you to add or remove the reference datum plane. Reference plane is available only if you extend the surface by specifying a datum plane.
• The Measurements tab—This tab is available only if you select Along Surface on the Extend tab. You can create a variable extension by adding and adjusting measurement points along the selected edge. By default, IDD adds only one measurement point, which extends the entire chain by the same distance to create a constant extension.
In addition, you can use this panel to specify how you want to measure the extension:
◦ 
—Measures the extension distance along the extended surface.
—Measures the extension distance along the extended surface.◦ 
—Measures the extension distance in the selected datum plane.
—Measures the extension distance in the selected datum plane.• The Options tab—This tab is available only if you select Along Surface on the Extend tab. You can specify one of the following options:
◦ Method—Lets you specify one of the following methods for the surface extension:
▪ Same—Creates an extension of the same type as the original surface. The original surface is extended past its selected boundary edge chain. This is the default.
▪ Tangent—Creates the extension as a ruled surface that is tangent to the original surface.
▪ Approximate—Creates the extension as a boundary blend between the boundary edges of the original surface and the edges of the extension.
◦ Extension side 1 or Extension side 2—You can specify one of the following options for the extension side:
▪ Along—Creates the extension along the side of the selected edge. If more than one edge is available for selection, select an edge from the adjacent collector.
▪ Normal To—Creates the extension normal to the connected boundary edge.