This is a tentative charter for a mailing list concerned with developing a style sheet language for the World-Wide Web.
The goal of the mailing list is to create or standardize on one or more languages for specifying the lay out of data that is marked up in SGML, so that it becomes understandable to people, under the following constraints and requirements:
Lay out must be specifiable for at least the following output media: computer screens (or windows) of vatious sizes and qualities, paper, braille paper, single-line braille reader, and speech generator.
The style language(s) must be applicable to a useful subset of all possible SGML documents, comprising — but not limited to — all HTML documents.
The language(s) must allow real-time formatting, i.e., formatting must be completed in a short enough time to be acceptable in an interactive program.
The language(s) must allow incremental formatting, i.e., for common documents it must be possible to format initial sections without waiting for later ones.
The language must be complete, in the following sense: given an HTML doc and another doc with exactly the same structure but differently named elements and attributes, it must be possible to format the second doc exactly as the first, for every possible layout of the first.
Note that it is not a requirement that formatting can start before the whole of the style sheet has been read (but it would be nice if it could...)
Some other things, not currently seen as requirements, but which may acquire that status if there is consensus:
The language should be text-based, so that it can be edited with simple text editors (altough specialized editors are preferred).
Compact, in order to save network resources and speed up downloading.
Suitable for `cascading', `subclassing' (or however it will be called), in order to encourage re-use, improve the chances of caching, and to offer writer and viewer simultaneaous opportunities to influence the lay out.
Easy to implement, so as to encourage competing implementations and tools; this applies to parsing the language as well as to implementing a formatter.
the collection of explicit instructions that determines the lay out of a document. Note that a style sheet need not be a single file, it can be the reuslt of combining other style sheets and fragments in various ways. The word `explicit' refers to the fact that there may be other things that influence the lay out, such as automatic modifications by the hardware
the visual, audible or tactile appearance of a document, meant (primarily or exclusively) for human senses. `Lay out' is often used in a more abstract sense: the appearance of a typical document, instead of of a concrete one.
the process of producing a lay out for a document, using a style sheet and possibly other (application dependent) information.
(Back) to style sheet overview
Bert Bos, 30 May 1995