5. Net Classes
Some nets in a printed circuitboard design can have specific layout requirements that you can determine during schematic design. Power nets might need to be of a minimum width to keep from overheating, impedance-controlled nets will need specific space and trace width, and high voltage nets must be kept a certain distance from other nets to prevent surface creepage or dielectric breakdown.
And where there is one net with specific design requirements, there are usually many more. Rather than keep track of each net individually, engineers assign a group of nets to a class, and create design rules for the class. Then, if they need to make a small design tweak later on, they can adjust all nets in a specific class at the same time.
While nothing in our current design really requires us to create special net-classes, we will go through the exercise so you'll know what to look out for in your next project.