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Inherited values where percent is legal

From: Karen Lease <klease@club-internet.fr>
Date: Thu, 04 Jan 2001 23:53:58 +0100
Message-ID: <3A54FF06.A6DF2976@club-internet.fr>
To: xsl-editors@w3.org

In working on FOP's FO property handling, I've run across a few issues
involving lengths which can be specified as percentages, especially when
the property can be inherited.
My list of such properties and their reference dimensions is as follows:

start-indent, end-indent             width of containing reference area
text-indent, last-line-text-indent   width of containing block
line-height                          font-size of the FO (inherits
font-size                            font-size of parent (inherits
leader-length                        width of content-rectangle of
parent area
leader-pattern-width                 width of containing box
provisional-distance-between-starts  width of containing box
provisional-label-separation         width of containing box

I know that the general rule is that computed values are inherited. This
is explicitly stated for font-size. On the other hand, for line-height,
when it is specified as a number the specification says that the
specified value is inherited. In this case, I'm inclined to treat a
percentage in the same way as a number (and a relative length too for
that matter).
For the other properties above, there is no specific mention of the
inherited value, implying that the computed value is inherited.

This bothers me a bit, especially for a property like leader-length
where the default value for leader-length.maximum is "100%". I would
feel more comfortable if the specified percentage value were inherited
and recalculated on each flow object.

I'd appreciate any explanations or justifications you can offer for

A related question: in the list above, there are several different ways
of designating the base length for a percentage. My interpretation is :
a) the dimension in question is always the content-rectangle, unless
explicitly stated otherwise,
b) "containing block" means the nearest block-area ancestor
c) "containing box" and "parent area" are basically equivalent and could
be either an inline-area or block-area.

Is this correct? Or is there some distinction I'm missing?

Thanks in advance for any information,

Karen Lease, FOP'er
Received on Thursday, 4 January 2001 17:51:29 UTC

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