Create a vertex in 3D space
The Vertex utility can be used to add a 3D vertex in 3D space that you can catch to while creating and modifying 3D curves. It is the 3D equivalent of the 2D Construction Point used when creating 2D profiles.
A 3D vertex is a wire part, for which you must give a name, but is in effect a 3D curve having zero length. You can specify a vertex by clicking a point on existing geometry or by specifying its coordinates. The Catch tool can be used to catch to existing geometry.
To create a vertex in 3D space,
1. Click 3D Geometry and then, in the 3D Point group, click 
Vertex 3D. The Vertex dialog box opens.
Vertex 3D. The Vertex dialog box opens.2. Type a name for Part.
3. Specify the vertex point:
◦ Click point(s) in the viewport.
◦ Catch to existing 3D geometry.
◦ Type the 3D coordinates in the user input line and press ENTER.
4. Click 
to complete the operation.
to complete the operation.