When you create a dimension style, you can create a child dimension style by selecting one of the Use For options, such as Linear, Angular, and Radius.

Caption: Angular and Radial are child dimensions of ISO-25.

If you haven’t used a child dimension style on an actual dimension, you can delete it with no harm done. If the child dimension style is in use, delete it by selecting the child dimension style and right-clicking to bring up the shortcut menu. Select Rename from the shortcut menu, then rename the style to create a parent dimension style.

Caption: Right-click on the child dimension you want to be rid of and select Rename.

Use the Properties command to change the dimension style for all dimensions that use the renamed style. Once that’s done, you can delete it.

AutoCAD’s Multiline command creates line objects that consist of as many as 16 parallel elements. For example, you could create a “pipe” multiline that creates the walls and inner diameter. The first step is to create a multiline style by typing Mlstyle at the command prompt or selecting it from the Format menu.

Caption: AutoCAD’s Multiline Style editor.

AutoCAD provides the Standard style as the default. To create a new multiline style, select New and enter a name.

Caption: Name your multiline style and select an existing style as a starting point.

Then select a style in the Start With window—that will be the style on which the new one is based. Select Continue to assemble the parts of your multiline style. Add elements and set their color and linetype (bylayer and byblock are options). The Offset value is distance from the multiline’s origin (or centerline). You can enter negative values. Next, set multiline properties such as fill color and start and end terminations. Options for terminations include a line drawn between the two outermost elements (you can set an angle for the line), an outer arc drawn tangent to the ends of the two outermost elements, and inner arcs drawn tangent to the ends of each pair of elements. You can specify angles for all of the ending options.

Caption: Assemble your multiline style by adding elements and caps.

Once you finish building your multiline, you can save it to an external file so it can be loaded in other drawings. You can either save to the default acad.mln file or create a new one.

To put your multiline into action, type in Mline at the command prompt or select it from the Draw menu. Before drawing, you can set justification and scale.

Justification options are Top (the default), Bottom, and Zero (origin). This determines where the line is drawn in relation to the cursor.

Multiline scale controls the overall width of the multiline using the current units. Multiline scale does not affect linetype scale. If you change the multiline scale, you might need to make equivalent changes to the linetype scale to keep dots and dashes in proportion.

Style lets you type in the name of an Mline style.

You then draw your multiline just as you would a regular line, by specifying points. Undo erases the last segment drawn, and Close connects the last segment drawn back to the starting point.

You can use most editing commands such as Move and Copy on multilines, but the Mledit command gives you specialized tools just for multilines. It brings up a dialog box with twelve different editing tools.

Caption: The multiline editing tools are arranged in columns: first, the crosses, then the Ts, then the joint and vertex tools, and finally the cut and join tools.

Some create crosses and Ts where multilines join. Just select the one you want to use, then the multilines. In the case of Ts, the first multiline selected is trimmed to form the T with the second line. You can create closed, open, and merged crosses and Ts.

Caption: Double crosses. The one at left is a closed cross, and the one at right is a merged cross.

The Corner Joint tool creates a corner joint to join two multilines. The multilines will be trimmed or extended to their intersection.

Caption: You can edit together two different styles of multilines, as shown by this corner joint.

You can also add and delete vertexes and create breaks in multilines. Weld rejoins multilines that have been broken.

Use the Fillet command as a quick way to intersect two straight lines. Start the command, type R and set the radius to 0, then select the two lines. They will lengthen (or shorten) to meet at their intersection.

In AutoCAD 2004 and beyond, you have the ability to edit xrefs in place by double-clicking on them. In many cases, this may not be such a handy feature. To turn off this capability, set the XEDIT system variable to 0.