Cs is a large and rapidly-expanding field; once you've become confident in your abilities to program moderate-sized projects, a lot of topics open up to you.

Now, if I have a moderate-sized project, I might use UML and a tool that supports UML to create enough class diagrams, sequence diagrams, and others to convey the design.

The rate of moderate-sized earthquakes is quite high, and there is a considerable likelihood that a magnitude 6 earthquake will cause damage if it strikes near a city.