Date of publication: 2017-09-05 14:18
Column groups allow authors to create structural divisions within a table. Authors may highlight this structure through style sheets or HTML attributes (., the rules attribute for the TABLE element). For an example of the visual presentation of column groups, please consult the sample table.
If an author specifies no width information for a column, a user agent may not be able to incrementally format the table since it must wait for the entire column of data to arrive in order to allot an appropriate width.
The direction of text in individual cells can be changed by setting the dir attribute in an element that defines the cell. Please consult the section on bidirectional text for more information on text direction issues.
The advantage of using the span attribute is that authors may group together information about column widths. Thus, if a table contains forty columns, all of which have a width of 75 pixels, it is easier to write:
Users may also want information about more than one cell, in which case header information provided at the cell level (by headers , scope , and abbr ) may not provide adequate context. Consider the following table, which classifies expenses for meals, hotels, and transport in two locations (San Jose and Seattle) over several days:
The wedding round table seating chart is used in weddings having round tables in the hall. The chart indicates the arrangement of the tables in the hall as a semicircle.
This specification does not require user agents to handle information provided by the axis attribute, nor does it make any recommendations about how user agents may present axis information to users or how users may query the user agent about this information.
The headers and scope attributes also allow authors to help non-visual user agents process header information. Please consult the section on labeling cells for non-visual user agents for information and examples.