You want to draw lines that have other shapes in them eg. --x--x--x--x or --o--o--o--o. These are sometimes used to define a fence. This has to be done with a 'repeating detail'. Here's how:
1. Make a family using the 'detail component' template. This will be the lines and shapes you want to repeat.
2. Load into project.
3. Go to the drafting toolbar. Choose Repeating Detail. Click on properties. Edit/New. Choose the new detail component family as the "Detail". You can set other things like spacing and rotation.
4. Start drawing the repeating detail as if it's a line. This "linetype" can be imported/exported using the "transfer project standards" tool. (I've blogged this as well under "Importing Wall Styles".)