# Description of Sketch Relations

The following table describes the entities that you can select for a relation and the characteristics of the resulting relation.

Relation Entities to select Resulting relations
Horizontal or Vertical One or more lines or two or more points. The lines become horizontal or vertical (as defined by the current sketch space). Points are aligned horizontally or vertically.
Collinear Two or more lines. The items lie on the same infinite line.
Coradial Two or more arcs. The items share the same center point and radius.
Perpendicular Two lines. The two items are perpendicular to each other.
Parallel Two or more lines.

A line and a plane (or a planar face) in a 3D sketch.

The items are parallel to each other.

The line is parallel to the selected plane.

ParallelYZ A line and a plane (or a planar face) in a 3D sketch. The line is parallel to the YZ plane with respect to the selected plane.
ParallelZX A line and a plane (or a planar face) in a 3D sketch. The line is parallel to the ZX plane with respect to the selected plane.
AlongZ A line and a plane (or a planar face) in a 3D sketch. The line is normal to the face of the selected plane.
Relations to the global axes are called AlongX, AlongY, and AlongZ. Relations that are local to a plane are called Horizontal, Vertical, and Normal.
Tangent An arc, ellipse, or spline, and a line or arc. The two items remain tangent.
Concentric Two or more arcs, or a point and an arc. The arcs share the same center point.
Midpoint Two lines or a point and a line. The point remains at the midpoint of the line.
Intersection Two lines and one point. The point remains at the intersection of the lines.
Coincident A point and a line, arc, or ellipse. The point lies on the line, arc, or ellipse.
Equal Two or more lines or two or more arcs. The line lengths or radii remain equal.
Equal Curvature Two splines. The radius of curvature and the vector (direction) matches between the two splines.
Symmetric A centerline and two points, lines, arcs, or ellipses. The items remain equidistant from the centerline, on a line perpendicular to the centerline.
Fix Any entity. The entity’s size and location are fixed. However, the end points of a fixed line are free to move along the infinite line that underlies it. Also, the endpoints of an arc or elliptical segment are free to move along the underlying full circle or ellipse.
Fix Slot A slot sketch entity. The entity’s size and location are fixed.
Pierce A sketch point and an axis, edge, line, or spline. The sketch point is coincident to where the axis, edge, or curve pierces the sketch plane. The pierce relation is used in sweeps with guide curves.
Merge Points Two sketch points or endpoints. The two points are merged into a single point.
Doubled Distance A centerline and any sketch entity. The sketch entity is dimensioned at twice the distance from the centerline.
Equal Slots Two or more slot sketch entities. The items have equal lengths and radii.
On Edge Edges of a solid. The edges of the solid are projected to the sketch plane using the Convert Entities tool.
On Plane Sketch entities on a plane. The sketch entities reside on the plane.
On Surface Sketch entities on a surface. The sketch entities reside on the surface.
Tangent to Face A sketch entity and a solid face. The sketch entity and face are made tangent to one another.
Traction   See Using Traction and Belts for Layout Sketches.
Torsion Continuity A spline and one of these entities:
• Spline
• Arc
• Conic or elliptical arc.
• Model edges that are linear, circular, conic, parabolic, elliptical, or spline-based.
The sketch entities obtain a smooth continuity relation with equal curvature and equal rate of curvature at the shared end point.
• When you create a relation to a line, the relation is to the infinite line, not just the sketched line segment, or the physical edge. As a result, some items may not touch when you expect them to.
• When you create a relation to an arc segment or elliptical segment, the relation is actually to the full circle or ellipse.
• If you create a relation to an item that does not lie on the sketch plane, the resulting relation applies to the projection of that item as it appears on the sketch plane.
• Additional relations are created automatically when you use Offset Entities and Convert Entities.