2. Language overview

2.1. Basic concepts

The basic concepts within SDF documents are:

Concept	Description
paragraph	one or more lines of text
phrase	a section of text within a paragraph
style	the type of a document, paragraph, phrase or table (e.g. H1)
macro	a command embedded in a document (e.g. !define)
variable	a named value (e.g. DOC_NAME)
filter	a rule to use when processing certain sections of text (e.g. table)
attribute	a named parameter of a paragraph, phrase or filter (e.g. jump)
expression	a literal or expression to evaluate (e.g. "Ian Clatworthy").

Further details about these are given below.