Section 3.1. Appearances Can Deceive | Data Networks: Routing, Security, and Performance Optimization

3.1. Appearances Can Deceive

Documents never look alike when displayed by a text editor and when displayed by a browser. Take a look at any source document on the Web. At the very least, return characters , tabs, and leading spaces, although important for readability of the source text document, are ignored for the most part when displayed by an HTML/XHTML browser. There also is a lot of extra text in a source document, mostly from the display tags and interactivity markers and their parameters that affect portions of the document but don't appear in the display.

Accordingly, new authors are confronted with having to develop not only a presentation style for their web pages, but also a different style for their source text. The source document's layout should highlight the programming-like markup aspects of HTML and XHTML, not their display aspects. And it should be readable not only by you, the author, but by others as well.

Experienced document writers typically adopt a programming-like style, albeit very relaxed , for their source text. We do the same throughout this book, and that style will become apparent as you compare our source examples with the actual display of the document by a browser.

Our formatting style is simple, but it serves to create readable, easily maintained documents:

Except for the structural tags such as <html> , <head> , <frameset> , and <body> , we place elements that structure the content of a document on a separate line and indented to show its nesting level within the document. Structural elements include lists, forms, tables, and similar tags.
Elements that control the appearance or style of text get inserted in the current line of text. These include basic font style tags such as <b> (bold text) and document linkages such as <a> (hypertext anchor).
Avoid, where possible, breaking a URL onto two lines.
Add extra newline characters to set apart special sections of the source documentfor instance, around paragraphs or tables.

The task of maintaining the indentation of your source file ranges from trivial to onerous. Some text editors, such as Emacs, manage the indentation automatically; others, such as common word processors, couldn't care less about indentation and leave the task completely up to you. If your editor makes your life difficult, you might consider striking a compromise, perhaps by indenting the tags to show structure, but leaving the actual text without indentation to make modifications easier.

No matter what compromises or stands you make on source-code style, it's important that you adopt one. You'll be very glad you did when you go back to that document you wrote three months ago searching for that really cool trick you did with...now, where was that?