Brush/

Mirror

reflects a stroke from one side of a mesh to the other, along the specified axis.

Off: strokes are not reflected.
X: strokes are reflected along the world space X axis.
Y: strokes are reflected along the world space Y axis.
Z: strokes are reflected along the world space Z axis.
Local X: strokes are reflected along the local space X axis.
Local Y: strokes are reflected along the local space Y axis.
Local Z: strokes are reflected along the local space Z axis.
Tangent: strokes are reflected across the topological center line of a topologically symmetrical model. To use tangent space mirroring on a mesh, you must first identify the mesh's topological center by selecting two faces that straddle the center line and then pressing Edit>Set Topological Center. For meshes with n-sided faces this procedure needs to be repeated on level1.