Explanation, or discussions, clarify and illuminate a particular Topic. They broaden the documentation’s coverage of a topic. page They are understanding-oriented. Explanations can equally well be described as discussions; they are discursive in nature. They are a chance for the documentation to relax and step back from the software, taking a wider view, illuminating it from a higher level or even from different perspectives. You might imagine a discussion document being read at leisure, rather than over the code. This section of documentation is rarely explicitly created, and instead, snippets of explanation are scattered amongst other sections. Sometimes, the section exists, but has a name such as Background or Other notes or Key topics - these names are not always useful. Discussions are less easy to create than it might seem - things that are straightforward to explain when you have the starting-point of someone’s question are less easy when you have a blank page and have to write down something about it. A topic isn’t defined by a specific task you want to achieve, like a how-to guide, or what you want the user to learn, like a tutorial. It’s not defined by a piece of the machinery, like reference material. It’s defined by what you think is a reasonable area to try to cover at one time, so the division of topics for discussion can sometimes be a little arbitrary.
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We are to admit no more causes of natural things (as we are told by Newton) than such as are both true and sufficient to explain their appearances. This central theme is basic to the pursuit of science, and goes back to the principle known as Occam’s razor: “if presented with a Choice between indifferent alternatives, then one ought to select the simplest one.” Unconsciously or explicitly, informal applications of this principle in science and mathematics abound.