# Axis
Generate an axis line for other command references, can be used to generate a centerline for cylinders, a rotating axis for rotating a boss, and so on.
Click the toolbar to 
open the Baseline Command dialog box, whose command interface is shown in the following figure.
# Mode of Operation
- A line/edge/axis: Create a reference line based on a line, edge, or axis.
Note：
A side line can be a solid, curved side line; an axis is an axis on the established coordinate system.
- Two planes：Based on the intersection of two planes, a reference line is created.
Note：
The face can be a solid plane, a cylindrical/conical bottom surface, a datum surface, and a surface selection is not supported.
- Two points/vertices: Based on the connecting line of two points, create a datum line.
Note：
Points can be sketch points, vertices, line midpoints, origin points.
4.Cylinder/conic: A cylinder/arc surface that creates a reference line that coincides with the axis.
Note：
Only one cylinder/arc surface can be selected
- Point and face: Based on a point and a face, create a reference line that passes through the point and is perpendicular to the face.
- Point and Line: Based on a point and a line, create a reference line that passes through the point and is parallel to the line.
- Corner bisectors: Select two lines and create a base line that coincides with the corner bisectors of both lines.
| The two lines are coplanar | The two lines are not coplanar | |
|---|---|---|
| Solution 1 |  |  |
| Solution 2 |  |  |
Note：
Two straight lines may not be coplanar, if not, a passing point must be selected.
Provide multiple solutions, click "next solution" to switch.
- Tangents of curves: Select two coplanar curves or a curve and a point to create a reference line that is tangent to the curve.
Note：
When displaying multiple reference lines preview, click "Next solution" to switch solution method.
When picking up a curve and a point, you can set "single cut mode, double cut mode".
