Reference lines are different from regular lines. They don't have start and end points. They will originate from a single point and then draw out from there.

Before we go through the process, familiarize yourself with these choices.

Line Width

Ray

A Ray will originate on the selected point and draw out in one direction from there.

Infinite Line

An Infinite Line will originate on the selected point and draw out in both directions from there.

Line Direction

You have three different directions to choose from.

Horizontal

The reference line will be drawn horizontally through the selected point.

Vertical

The reference line will be drawn vertically through the selected point.

On Vector

The reference line will be drawn through the reference point with a second point used as the vector.

Process

Ray Horizontal

Select a starting point. This can be a key point, reference point or curve point.

In this example, we are choosing a Ray.

Next we will choose Horizontal.

The program will draw a line extending from the point horizontally in one direction. If you want it to go the other direction, select Other Side.

Infinite Line Vertical

In this example, we'll select and Infinite Line vertically.

Select a starting point. This can be a key point, reference point or curve point.

We will choose to draw an Infinite Line.

Next we will choose Vertical.

The program will draw a line originating at the point extending in both directions vertically.

On Vector

Lastly, we'll draw an Infinite Line that goes through a point using another point as the vector.

Select a starting point. This can be a key point, reference point or curve point.

We will choose an Infinite Line.

Next we will choose On Vector.

The system will ask for us to select a vector point.

The program will draw a line originating at the point extending in both directions using the second point for the vector.