TABLE discussion Al Gilman ([1]asgilman@access.digex.net) Thu, 16 Oct 1997 13:22:13 -0400 (EDT) * Messages sorted by: [2][ date ][3][ thread ][4][ subject ][5][ author ] * Next message: [6]Al Gilman: "DESC discussion" * Previous message: [7]Al Gilman: "OPTION discussion" _________________________________________________________________ From: Al Gilman Message-Id: <199710161722.NAA27813@access2.digex.net> To: w3c-wai-ig@w3.org Date: Thu, 16 Oct 1997 13:22:13 -0400 (EDT) Subject: TABLE discussion TABLE Making TABLEs comprehensible BACKGROUND: Tables have been a serious problem for people using audio browsing. Today HTML pages use tables for two purposes: to layout pages, and to present tabular information. Both uses present accessibility problems. When tables are being used purely for visual layout, the issue is mainly one of reading order and style sheet are probably the best way to improve accessibility in that situation. This message will focus on how to improve the browsing experience for tabular information. Tabular information generally consists of headers and data. Imagine using a speech-based browser to examine a table designed for visual browsers. If there are more than just a few cells it will be easy to forget the headers as you move from cell to cell. If there was some way of knowing which headers are appropriate to this cell, then perhaps you could ask for these headers to be spoken, either on request, or automatically when you move to a new cell. This will work much better if the author has been so kind as to provide abbreviations for headers. We also need to improve communication between applications and screen readers. Sometimes what browsers do to de-tabulate table contents works better than the tabular presentation; sometimes you really have to browse the material in its two-dimensional pattern of relationships to get what you are being told. The HTML working group has introduced new features in version 4.0 to fix this situation, and the HC working group has recommended that the WAI ask for a little more. PROPOSAL: The WAI Browser Guidelines group should seek functions from browsers which break down a table into alternate presentations. One useful alternate presentation is a hierarchical list such as is used for listing tables of contents. The WAI Markup Guidelines group should develop recommended CLASS values to be used in TABLEs to indicate when tables should be read by rows, when by columns, and whatever other structural classes they find necessary to guide the selection of non-tabular presentations. The AXIS attribute in HTML can be used to associate table cells with a conceptual category such as dates, expense catetories, etc. This can be done on the individual cell or indirectly by an AXIS value on a header cell which describes a cell in the body of the table. This should be used to guide browser functions that list table contents. For audio browsing it is important to have a clear indication outside the visual layout of which headers go with which body cells in a table. The SCOPE and AXES attributes, together with defaulting rules, should be used to capture this information. The WAI Browser Guidelines and Markup Guidelines can be used to clarify defaulting rules and compatible markup practices using SCOPE, AXES and CLASS. The proposals for specifying which headers are relevant to each cell are designed to allow these headers to be grouped and for these groups to be ranked. This is intended to give implementors the freedom to treat the table as a hierarchy that is independent of the visual layout chosen for windows based browsers. The idea is to allow large and complex tables to be browsed in a similar way to browsing file system directories, with the ability to hide or expose levels of detail. The scope attribute allows authors to state whether a given header applies to the current row, column, row group or column group. This takes advantage of new table features in HTML 4.0 for specifying column properties and for grouping rows and columns. Scope works well for most simple tables. Here is an example: The summary attribute is used to summarise the role and structure of the table: "History courses in Bath arranged by course name, tutor, summary, code and fee" Each row is represented by the TR element. The first row contains column headers. These are marked up using the TH element, each of which has scope="col" to indicate its role as a column header. The abbr attribute is used to provide an abbreviation for longer headers. The next row is marked up as: The TD element is used to markup each data cell. The first cell in the column gives the course name. Since this is considered to be helpful when browsing subsequent cells in the row, it has been marked up with the scope attribute, this time with scope=row to indicate that its relevant to the rest of the current row. The scope attribute is of limited generality. For cases where it breaks down, we propose an attribute called "axes" that is used to list the ID's of all relevant headers. The name is based upon the idea of thinking of tabular data in terms of values at points in an n-dimensional space. The headers then form marks along the axes of this space. An attribute called "axis" is used to supply a name indicating which axis a given header belongs. Scope and axes are interelated and implementors are likely to map them both into the same internal model of which headers are relevant to each cell. Finally, there is interest in being able to associate tables with meta-information that describe richer semantics about the table. The WAI Browser Guidelines group should seek functions from browsers which support browsing tables on a cell-by-cell basis. Moving through the table by one or some number of cells up, down, backwards, and forwards are desirable. A more extensive strawman operational model is available. See the REF&META discussion for more on this, in particular how it relates to RDF. The W3C should ensure that a table can be linked to a data dictionary or other resource providing additional documentation of the data usage in the table. One way to do this in HTML is to provide the capability through LINK elements. See the REF&META discussion for more on this. Finally, the SUMMARY attribute should be suitable to be spoken after the CAPTION element, when there is a CAPTION for a table. This should be made clear in the WAI Markup Guidelines, and in the prose of the HTML specification as well. QUESTIONS: These are representative questions the Interest Group may wish to discuss. How would the proposed markup be applied to this table (give URL)? Who has experience with browsers that support cell-by-cell browsing, and how did it work? FOLLOW UP: Please discuss this issue by sending email to w3c-wai-ig@w3.org . Include the symbol TABLE in the subject heading of your message, to help other subscribers organize the volume of mail we hope this will generate. _________________________________________________________________ * Messages sorted by: [8][ date ][9][ thread ][10][ subject ][11][ author ] * Next message: [12]Al Gilman: "DESC discussion" * Previous message: [13]Al Gilman: "OPTION discussion" References 1. mailto:asgilman@access.digex.net 2. http://lists.w3.org/Archives/Public/w3c-wai-ig/1997OctDec/index.html#5 3. http://lists.w3.org/Archives/Public/w3c-wai-ig/1997OctDec/thread.html#5 4. http://lists.w3.org/Archives/Public/w3c-wai-ig/1997OctDec/subject.html#5 5. http://lists.w3.org/Archives/Public/w3c-wai-ig/1997OctDec/author.html#5 6. http://lists.w3.org/Archives/Public/w3c-wai-ig/1997OctDec/0006.html 7. http://lists.w3.org/Archives/Public/w3c-wai-ig/1997OctDec/0004.html 8. http://lists.w3.org/Archives/Public/w3c-wai-ig/1997OctDec/index.html#5 9. http://lists.w3.org/Archives/Public/w3c-wai-ig/1997OctDec/thread.html#5 10. http://lists.w3.org/Archives/Public/w3c-wai-ig/1997OctDec/subject.html#5 11. http://lists.w3.org/Archives/Public/w3c-wai-ig/1997OctDec/author.html#5 12. http://lists.w3.org/Archives/Public/w3c-wai-ig/1997OctDec/0006.html 13. http://lists.w3.org/Archives/Public/w3c-wai-ig/1997OctDec/0004.html
Community Courses - Bath Autumn 1997
Course Name Course Tutor Summary Code Fee
After the Civil War Dr John Wroughton The course will examine the turbulent years in England after 1646. 6 weekly meetings starting Monday 13th October. H27 £32