The BREAKLINE command is an Express Tools command that creates a line to represent a partial view of a drawing that looks something like this:

Type BREAKLINE on the command line and it will prompt you with this:

Specify first point for breakline or [Block/Size/Extension]:

B for Block
You can change the linework for a breakline by specifying a different block. It will prompt you:

Enter the block name for breakline symbol :

…asking you to type in a path to a block. If you simply type ~ a dialog box will appear so you can browse instead of typing the entire path to the block you want to use.

There are a couple requirements to making your own breakline block. You need linework and two points on the defpoints layer. The linework is what will be visible. The two points designate where it needs to break. Here is an example of linework with two points on the defpoints layer, highlighted with grips:

If you don’t include two points on the defpoints layer in your block, you will receive this message when you try to use it with a breakline:

S for Size
Be aware that the size of the breakline is multiplied by the DIMSCALE value. For example if you have DIMSCALE set to 1 and the breakline size is set to 0.5, the breakline will measure 0.5 units.

This is important because you might encounter this problem when clicking two points to create the breakline:

*Invalid* Points are too close together to insert break symbol.

If you get this check to make sure both the breakline size and the DIMSCALE value are set correctly.

E for Extension
Just like the Size setting, the Extension value is also multiplied by the DIMSCALE value. For example if you have DIMSCALE set to 1 and the breakline size set to 0.04, the breakline will measure 0.04 units.

Breaklines are not dynamic. If you change your DIMSCALE, your breaklines will not automatically update. You can, however, erase them and redraw them.