Encoding document appearance: rendition ladders overview [115]

Abstract

General notes on the use of the rendition ladder in the rend= attribute, overview of keyword/value structure

Discussion

The WWP encodes information about the appearance of the printed document using the TEI rend= attribute. This attribute is allowed on all TEI elements. Renditional information is fairly complex and may include multiple facts about a given element, such as indentation, typeface, capitalization, alignment, and many other details. In order to fit all of this information into a single attribute value, the WWP has developed a system of “rendition ladders”, in which all renditional information is encoded within a single rend= attribute in a structured form. This system replaces one in which each separate piece of renditional information was encoded in a different attribute, which was cumbersome and imperfect.

Each renditional quality (typeface, indentation, alignment, etc.) is given a keyword which is in turn paired with a value or a series of arguments; these pairs of keywords and values/arguments are strung together to make the renditional attribute value.

Keyword values are always surrounded with parentheses. Keyword-value pairs are separated from one another with a space, but this is for readability only; the computer will ignore this space when parsing the encoding. However, within a keyword value, where the value is a string of characters to be printed (such as in the pre or post keywords, which indicate characters printed before and after the element), a space will be regarded as part of the character string. Thus in the following examples, 1 and 2 are equivalent, but 3 and 4 are not.

1. rend="slant(italic) case(smallcaps)"

2. rend="slant ( italic)case (smallcaps)" [space here is not significant]

3. rend="pre(&mdash)"

4. rend="pre( &mdash )" [space here is significant]

The entire renditional attribute value, like all other attribute values, is enclosed within quotation marks.

It does not matter what order the keyword-value pairs appear in.

It is only necessary to specify the keyword-values which differ from the defaults: either the defaults set by the encoder in the tagsDecl or the global defaults which are assumed about the text. For instance, we assume that unless otherwise specified, the value of the indent keyword will be 0.

Specifying a keyword twice is allowed, although we’d normally find it a bit silly. In such cases, the last occurrence (as you read left-to-right) is used, and the others are ignored. Thus an element with rend="indent(6) slant(italic) indent(5)" would be considered to have been indented by 5.

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