Hello,
This message provides some background and clarification to the issue
"Border-spacing property of enhanced layout not effective" that's part of
the CSS Print Profile specification
(http://www.pwg.org/hypermail/xp/0098.html)
CSS has two different styles for rendering the lines between cells in a
table, i.e., the table cell borders. The styles are:
- separate borders, where each cell has a distinct border line, and
- collapsed borders, where there is a single line separating each cell.
These styles are controlled by the border-collapse property, which is not
one of the required properties, even in the enhanced layout set. The
separate borders style makes use of the border-spacing property, which is
ignored in the collapsed borders style. The border-spacing property is part
of the enhanced layout set.
I want to clear up the ambiguity of
1. requiring support for the border-spacing property,
2. not requiring the border-collapse property, and
3. not stating the a printer should render tables using the separate borders
style.
There are two possible ways to clarify this ambiguity:
1. state that a printer must always render tables using the separate borders
style, and 2. state the enhance layout printers should support both styles
and the border-collapse property that controls the style application.
Minimally conforming printers must always render tables using the separate
borders style.
There is one extra complexity to supporting the collapsed borders style:
what happens when two lines of different style occupy the same area between
and around cells. In the collapsed border style only one line is rendered
between and around table cells. However, it's possible to specify different
borders for different parts of the table. Then the printer must support the
functionality described in "Border conflict resolution"
(http://www.w3.org/TR/REC-CSS2/tables.html#border-conflict-resolution).
One benefit of clarifying this ambiguity is that the specification can then
suggest how a printer should handle empty cells, thereby giving some
consistency across all printers.
My personal opinion and that of others at HP is that the second of the two
possible clarifications be used -- the enhanced layout set include the
border-collapse property.
Jim Bigelow,
Editor: XHTML-Print & CSS Print Profile
IEEE, Printer Working Group
http://www.pwg.org/xhtml-print
Hewlett-Packard
208-396-2068
jim.bigelow@hp.com
This archive was generated by hypermail 2b29 : Fri Jan 03 2003 - 12:46:28 EST