Dear XSL Editors, The XSL-FO 1.1 Recommendation gives some details about how the border-separation property for tables should be handled, but it is not clear in my opinion where the half of it associated to the table should lie.
As a picture is still the simplest way to illustrate the problem, please have a look at the following example and the attached picture (see below for the formulas): <fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format"> <fo:layout-master-set> <fo:simple-page-master master-name="page" page-height="10cm" page-width="15cm" margin="1cm"> <fo:region-body background-color="#ffc000"/> </fo:simple-page-master> </fo:layout-master-set> <fo:page-sequence master-reference="page" font-size="12pt"> <fo:flow flow-name="xsl-region-body"> <fo:table width="100%" table-layout="fixed" border-collapse="separate" border-separation="8pt" border="4pt solid black"> <fo:table-column number-columns-repeated="2" column-width="proportional-column-width(1)"/> <fo:table-body> <fo:table-row> <fo:table-cell border="4pt solid black"> <fo:block>Cell 1</fo:block> </fo:table-cell> <fo:table-cell border="4pt solid black"> <fo:block>Cell 2</fo:block> </fo:table-cell> </fo:table-row> </fo:table-body> </fo:table> </fo:flow> </fo:page-sequence> </fo:root> So, in the attached picture, which version is correct? First, in section 4.4.1, “Stacked Block-areas”, the graphic shows a space-start trait but it is explained nowhere how its value should be computed. From the graphic we can infer the following formula: space-start = start-indent − border-start − padding-start Still, it is not clear whether we are referring to traits or properties for border and padding. If I’m correct the padding-start property always directly maps to the padding-start trait. But this may not be the case for border-start, see below. So, let’s assume the following: (1) space-start(trait) = start-indent − border-start(trait) − padding-start (Let’s note that Section 4.2.2 does not define any trait called start-indent, so this is always the property which will be used.) Then Section 4.2.3, “Geometric Definitions”, states that, for block-level areas, “the allocation-rectangle extends [...] outside the content-rectangle in the inline-progression-direction by an amount equal to the end-indent, and in the opposite direction by an amount equal to the start-indent.” For simplicity, let’s assume that the writing direction never changes. Given a block-area B, let’s call xa the offset of the start-edge of its allocation rectangle from the start-edge of the content-rectangle of its closest ancestor reference-area. Likewise, let’s call xc the offset of the start-edge of its content-rectangle. Section 4.2.3 states that: (2) xa = xc − start-indent Then Section 4.4.1 states that: xa = start-indent + start-intrusion-adjustment − border-start − padding-start − space-start Since this section is all about traits, let’s assume we have the following: (3) xa = start-indent + start-intrusion-adjustment − border-start(trait) − padding-start − space-start But since space-start can be inferred from start-indent thanks to equation (2), we can simplify (3) into the following: xa = start-indent + start-intrusion-adjustment − border-start(trait) − padding-start − (start-indent − border-start(trait) − padding-start) which will simplify into the following: xa = start-intrusion-adjustment and xc = start-intrusion-adjustment + start-indent which means that if start-indent = 0, then the start-edge of B’s content-rectangle will coincide with the start-edge of the content-rectangle of the closest ancestor reference-area. Buth then, why having kept the formula in its original, unsimplified form? Now about tables. Section 6.7.3, “fo:table” says that in the separate border model the border of the table is composed of half the value of the border-separation property plus the border as specified by the property. Which would mean that the border-start(trait) would, in this particular case, be different from the border-start(property): border-start(trait) = border-start(property) + border-separation.inline-progression-dimension / 2 That’s why it seems important to me to know whether we are speaking of traits or properties in the formulas above. If both formulas use the same value (trait or property), then we have the result #1 on the attached picture. If formula (1) uses the trait and formula (3) uses the property, then the simplification will give: xa = start-indent + start-intrusion-adjustment − border-start(property) − padding-start − (start-indent − border-start(trait) − padding-start) = start-intrusion-adjustment + border-separation.i-p-d / 2 Leading to result #2 in the attached picture, which is a sensible result. And if formula (1) uses the property and formula (3) the trait, we get result #3 which is probably less likely to be expected. Finally, Section 6.7.3, “fo:table” and Section 6.7.10, “fo:table-cell” mention the “table grid boundary line”, but it is unclear where this line should actually lie, especially with respect to the table padding. There seems to be an inconsistency since Section 6.7.3 states that “the first [border component], which is placed with the inside edge coincident with the outermost table grid boundary line, has the width of half the value for the ‘border-separation’ property”. And Section 6.7.10 states that “the first [border component], which is placed with the outside edge coincident with the table grid boundary line, has the width of half the value for the border-separation trait”. Then where shall the padding be placed? The only consistent way to resolve this issue in my opinion is to make the padding coincide with the table outermost grid boundary line. See the attached picture as an illustration (where case #1 from above has been selected). It might be helpful to add an indication with this respect in the Recommendation. Thanks, Vincent Hennebert -- Vincent Hennebert Anyware Technologies http://people.apache.org/~vhennebert http://www.anyware-tech.com Apache FOP Committer FOP Development/Consulting