Many design choices are involved in the process of producing a document. For example, the copy editor chooses names for the logical parts of the document and communicates them to the graphic designer and compositor on the marked-up manuscript. The graphic designer chooses the typographical parameters for these marked parts of the manuscript and communicates them to the compositor on type-specification sheets, such as the one shown in Figure 1. The compositor acts on the mark-up codes, using the type specifications, and enters typographical formatting codes in the typesettable file.

All of these choices influence the publishing style of the organization. The American Heritage Dictionary's definitions of `style' and `style book' help clarify what style means and how it can be used:

Each publishing house develops its own house style, a way of doing things that will distinguish documents from that publisher. In the publishing experiment described in One Book/Five Ways, the University of Toronto Press provided the most concise set of composition style guidelines, covering the following topics:

People at different levels contribute to a publisher's distinctive style. The editorial staff establishes the guidelines for authors and copy editors, such as recommended forms of presentation, spelling, language usage, or the avoidance of vertical rules in tables. Graphic designers select the typography and layout for book designs. The composition staff determines the final typesetting choices through interpreting the typographic specifications.

A publisher's style is developed through an iterative process. The high level plan is established by the publisher and the editorial staff; they request a certain `look' or `feel' for a publication. The graphic designer reduces that high level plan into more specific guidelines, but the compositor still has some freedom to interpret typographic choices. The result is sample pages. These pages are passed up the chain for approval and are returned for correction. The changes iterate among publisher, graphic designer, and compositor until the publishing staff finally `sees' what they want. For large documents, this leads to inconsistencies in how variations not covered in the sample pages are handled, or even differences due to different people working on the manuscript. The solution has traditionally been ``Try it again until you get it right.''

For automated composition systems that rely on algorithms to carry out repetitive actions, the traditional design process makes it hard to extract the formatting algorithms from style guidelines. The guidelines are expressed in terms of what people are doing, rather than the process of doing it, or the cause and effect decisions that lead to the result. Therefore, it takes several iterations with sample pages that cover all the expected situations before a creative programmer can express the style rules as an algorithm.

Style may seem to affect or control more than just the appearance of a document. For instance, consider the choice between Canadian and American spelling, something that might be treated as a style choice. Clearly different spellings contain different letters, as in `colour' versus `color', `labelling' versus `labeling', but the same letters may appear in a different order, as in `centre' versus `center'. The concept of style must accommodate these apparent changes in substance.

We need to realize that style can accomplish changes at many different levels. The change in spelling does not affect the meaning of the sentence containing those words, and therefore the substance of the meaning remains constant while the spelling varies. In fact, many Canadian and American readers easily pass over these different spellings. The style may have changed the characters but not the meaning of the words.

Consider the language processing tricotomy of lexical, syntactic, and semantic analysis. Style can be seen to affect primarily the first two stages of analysis. Style at the lexical level affects a token's appearance, such as the choice of spelling. More common lexical style changes are the use of distinctive typefaces for section headings, the inclusion of whitespace above and below section headings, etc. In fact, most typographic parameters fall into this lexical category of style.

Style at the syntactic level affects the order of information in the document. One example is the order of names in a bibliographic citation; one style places the surname before initials, while another style places initials before the surname. Another example of syntactic style is the placement rule for parts of a document during page layout, such as locating figures at the top or bottom of a page and collecting all footnotes at the bottom of each column.

Style is also possible at the semantic level by providing different readers with different views of the document. For instance, a document on how to use the Cedar mail system on a new kind of file server [van Leunen, One Document] was prepared for readers with different backgrounds. The document contained written modules of information for one of three kinds of audiences: those who had never used the mail system, those who had used the mail system but stored their files locally, and those who had used the mail system and had some experience with the new file server. A map of which modules applied to which experience categories was used to compile three versions of the document from the various modules. Cargill presents similar ideas for managing different views of software source code [Cargill, Views]. In his scheme, multiple software versions for differently configurable systems were maintained in the same file structure. Depending on the configuration desired, different software versions would be extracted.

Another style dimension is differentiation in media. Traditional printing processes provide some variation in colors and papers, but other reproduction technology and electronic documents span a broader range of possibilities. Documents that become projection slides, posters, or video displays represent some of these.

The notion of device independence in computer graphics can be applied to document formatting. The survey article on document formatting [Furuta, Survey] presents the notion of a `view' of a document as the device-independent post-processing of a formatted document for a particular device. However, media and device capabilities may influence the appearance and readability of information in a document. In this case, device independence is less desirable. Rather, we wish to reformat the document to take advantage of device characteristics or, put another way, to change the style to suit the medium in which the information will be presented.

Low-resolution devices without color must obviously use different techniques than high-resolution color laser printers. Type families are hard to distinguish on low-resolution devices: 8-point Times Roman on a display screen is difficult to distinguish from any other serif typeface (such as Garamond or Baskerville) because there are so few `bits' available to display subtle differences. A color image may lose a great deal when viewed in black and white, especially on low-resolution devices that display only a few, if any, grey levels.