|CHWP B.13||Tompa, "Experiences with the OED"|
One major advantage gained by adopting descriptive markup is the flexibility to format a text to suit various media and uses (Fawcett, 1989). In particular, the tagging used in the OED does not bind a display engine to produce a particular form. In fact, it is left completely to the users' discretion to design text formats that will display extractions from the OED to best advantage. To this end, a user must create a specification file, or style sheet, that correlates tags in the text with presentational features -- more typically a user requests that some pre-defined specification file is to be applied. This style sheet is then interpreted by the Lector text display system (Raymond, 1990), to produce a presentation form on a screen (through the X Windows System).
For the OED, we have created a file that includes style sheets for standard display (mimicking the printed style of the OED) (Figure 4); standard display but with quotations suppressed; one-per-line display of quotations only; standard display of definitions only or of etymologies and dates only; outline displays of the sense structure showing the upper skeleton only, the complete sense skeleton (Figure 5), or the skeleton with all lemmas shown as well; and a standard display augmented by display of all tags (Figure 6), as well as a completely uninterpreted dump of the characters (including tags) as they are stored.
A display specification for Lector is itself represented as a tagged text (Lector, 1990). After declaring the fonts that are to be made available to the display device, the file includes a series of style sheet declarations (indicated by <Spec>...</Spec>). Each style sheet is assigned a name and its default display mode.
<Spec> <Name>Standard</Name> <Family>Times</Family> <Type>Roman</Type> <Size>14</Size> <PrText>on</PrText> <PrTag>off</PrTag> ... </Spec> <Spec> <Name>Quotes Only</Name> <Family>Times</Family> <Type>Bold</Type> <Size>12</Size> <PrText>off</PrText> <PrTag>off</PrTag> ... </Spec>Following that, for each tag that can appear in the text, the style sheet indicates what typesetting is to be done: change in font or style, line break, indentation, insertion of a character string, suppression of text from the file, and so forth. For example, the "Quotes Only" style sheet includes the following directives:
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