The dollar sign, caret, backslash, and braces are all part of the mark-up language. LaTeX interprets the symbols between dollar signs to be a mathematical equation, and within an equation the caret symbol means ``the next character is a superscript.'' The string it means ``print the following text (up to the next closing brace) in italics.''
The mark-up language for Mosaic documents is the Hypertext Mark-up Language (HTML). HTML is extremely simple compared to LaTeX or Postscript. There are commands to print text in different styles (e.g. boldface or italics) and to create section headings, but little else in the way of formatting the output. The main distinction of HTML is that it has a way to define links to other documents.
To continue the example above, suppose you want to make the word ``alphabet'' a link to a glossary that defines the word. In HTML you would write
... from an <A>alphabet</A> of <I>a</I> symbols ...HTML uses angle brackets to denote formatting commands. In this example, the item between <A> and </A> becomes an anchor (the beginning or ending of a link).