ABSTRACT
The highest level of construct of the language is a document, which is intended to represent a unit in some outer context. Two types of document are available, to allow different styles of writing. In the more structured style, a document is a sequence of 1 or more modules (a module list), a module being a fairly self-contained unit with an identifier, an interface part defining the external properties of the module, and a set of definitions. This style is described in chapter 10. A freer style is available where a document is just a sequence of definitions (a definition block list), grouped into definition blocks; this is called the flat language and is almost independent of the structuring features. The flat language is described in chapters 3 to 9 inclusive.
