Structure in Functional TextThe structure of a functional document can be analysed from three different points of view: the presentation of information content, the development of argument, and the grammatical and stylistic cohesion of the text. To be effective, a document must be well structured in all three ways. This paper explores the relationships between the three types of structure, and suggests ways in which the writer can make the three types mutually reinforce each other. The resulting documentation will rate highly in ease of retrieval, ease of comprehension, and ease of use.
What is Structure?A structure is a construct, or combination of components, formed according to consistent and observable principles. Structure - the property possessed by structures - is principled, or systematic, organisation. The idea of a combination of components is fundamental to language. We combine words into phrases, phrases into clauses, clauses into sentences, sentences into paragraphs, paragraphs into chapters, chapters into books. Structure, then, implies that we start with smaller bits and end up with bigger bits (see Figure 1).
Figure 1: Structure in Language Principles and the rules of grammar are just a rigorous form of principle determine how these combinations are made. A random collection of words, like "rhubarb manual decided", has no governing principle and is therefore not structured. Principles must be consistent (within reasonable limits): we must be able to distinguish between the effects of principle and those of chance. Principles must be observable (and observably consistent): we must be able to see them at work, rather than merely predicting their effects. For our purposes, concerned as we are with functional texts, structure can be found at three different levels. We can find principles at work in the way sentences combine to form text, in the way information items combine to represent reality, and in the way propositions combine to form an explanation or argument. We cant completely isolate these three aspects, because they do not correspond to completely separate features of language; in particular, the reader has to deal with all three concurrently. We can, though, isolate and examine the underlying principles.
Aspects of StructureIt makes sense to look at language-based structure in terms of semantics, or information content (meaning); rhetoric, or argument; and cohesion, or textual unity. Well look at each in some detail.
Semantic StructuresThe fundamental semantic structure can be usefully described as topic/comment, though the particular tradition I work in prefers the terminology theme/rheme for sentence structure. In fact, the two are not identical; but they are close enough for our purposes, and I shall use both pairs of terms interchangeably. In a simple declarative sentence, the theme corresponds to the subject, and the rheme to the predicate. In a conventional paragraph, the theme corresponds to the topic sentence, and the rheme to the remainder. The theme or topic is what comes first: it is "what we are talking about". The rheme or comment follows: it is "what we are saying about the theme or topic".
Thematic LinksIt is a general principle of clear writing that we should introduce new material by associating it with old material. We put old (or given) information in the theme, and make our new information the rheme. Once we have introduced that new information, it becomes old, so we can then use it (or something derived from it) in theme position to introduce further new material. Like this: (1) The power switch is located at the top right-hand comer of the front panel. (2) It is marked with two symbols: 0 and 1. (3a) Push the switch towards 1 to turn power on. Push it towards 0 to turn power off. (3b) To turn power on, push the switch towards 1. To turn power off, push the switch towards 0. It is interesting to see how the thematic links are developed differently in 3a and 3b, as illustrated in Figure 2. These examples show clearly how "new" information, once presented, becomes "old" and thus available for reuse. These examples also show how the "new" slot can be used to reprocess old information, presenting it in a new light. You might care to decide whether you prefer 3a or 3b; the nature of the thematic links might then help to account for your choice.
Figure 2: Variations in thematic linkage
The Outline as a Semantic StructureThe effect of thematic links within a paragraph is that the theme of every sentence in the paragraph should be (directly or indirectly) derived from the topic sentence (see Figure 3). But where does the topic sentence itself come from?
Figure 3: Thematic Links in the Paragraph The next larger unit of text the construct which is a combination of components called paragraphs may be a subsection, a section, or a chapter. For simplicity, lets call it a section. Every section should begin with what amounts to a topic paragraph one that sets out the scope or purpose of the section. The topic sentence of each paragraph should then be derived (directly or indirectly) from the topic paragraph. Of course, the sections combine into a larger unit called a chapter, and the chapter must have its topic section. In practice, the topic section may not be separately labelled, and it may consist of only a single paragraph; but it will certainly precede the first "real", information-bearing section. This leads inevitably to the question: where does the chapter get its topic section from? The answer will vary in detail, but will be consistent in principle: the topic section will derive from something central to the whole book. That "something central" may be expressed in a preface, an introduction, or simply the books title. Now the books title can be thought of as a label given to the entire text. In the previous paragraph, I referred to sections as being "separately labelled". At that point, of course, I was thinking of headings (whether numbered or not). A label a heading or title can be thought of as a condensed statement of the topic of whatever textual unit we are talking about. If you look carefully at the table of contents of a well-organised book, you will see that it reflects the thematic links between the book as a whole, each chapter of the book, and each section of each chapter. If each heading had been written out "in full", as the topic of the relevant unit, we would be able to trace the links quite easily. Such a table of contents would be rather unwieldy, so we dont do it (though eighteenth-century novelists often did), but we use the condensed headings as a summary representation of the overall semantic structure. Once we have defined the topic of each section, we can then relate each paragraphs topic sentence to that section topic. The complete outline, down to the level of individual paragraphs, can should display thematic unity. See Figure 4 for the complete semantic structure of a tightly-organised book.
Figure 4: Semantic Structure of a Book
Rhetorical StructuresIn present-day Australia, "rhetoric" is something of a dirty word: we generally interpret it as "the trick of taking the audience for a ride". In classical Greece, however, it was "the art of constructing an argument". To the Greeks it was an important skill, and medieval scholars regarded it as one of the "liberal arts". In modern America, the word retains its original meaning, and the subject is taught in schools and universities. The fact that rhetoric is in bad odour in this country is our loss. The fundamental principle of rhetoric is the development of a coherent line, or "thread", of argument. The rhetorician starts with a set of principles which may be subjective or axiomatic, explicitly stated or tacitly assumed and develops logical consequences which lead inexorably to the required conclusion. In technical discourse, we are not concerned with persuasion (though some forms of functional text are), but we are concerned with logical consequences. We are concerned with developing not a persuasive argument, but an informative argument, or explanation: we are concerned with building a coherent picture in the readers mind. Clearly, thematic links contribute to that coherence in one sense, but they do not necessarily reveal logical relationships. That is the task of rhetoric.
Logical LinksThere are six kinds of logical link between items of information: Additive, Alternative, Adversative, Causal, Circumstantial, and Equivalent. They work like this:
If two items are independently true, but have a cumulative effect, they are in an additive relationship.
There are 1000 millimetres in a metre. There are 1000 metres in a kilometre.
If only one of a number of items is true or applicable, they are in an alternative relationship.
You can install this software from a diskette. You can install this software from a CD-ROM.
If two items are true, but there is (or appears to be) a contrast or conflict between them, they are in an adversative (sometimes called contrastive) relationship.
The standard editorial reference for Australian writers is the AGPS style Manual. Writers aiming at international markets should refer to the Chicago Manual of Style.
If one item causes or is caused by the other, they are in a causal relationship.
[Brand X] photograph paper is insensitive to light in the wavelength range [nnn] [ppp] Angstrom. It should be handled only under the [brand Y] [model Z] safelight.
If one item simply gives more detailed information about the other, they are in a circumstantial relationship. Typical circumstantial relationships are spatial and chronological.
The power switch is at the top right-hand comer of the front panel. Immediately to the left of the switch, there is a power warning light.
If one item is ess