AH Formatter / XSL Formatter
Q&A

例を挙げて説明します。 次のFOではこのような問題が起きます。

<fo:block font-size="8pt">
<fo:float float="start">
<fo:block>
<fo:inline font-size="30pt">H</fo:inline>
</fo:block>
</fo:float>ere, we have a drop cap that should be 3-lines high.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
</fo:block>

上記のFOを修正してみました。

<fo:block font-size="8pt">
<fo:float float="start">
<fo:block space-after="-8pt" space-after.conditionality="retain">
<fo:inline font-size="30pt">H</fo:inline>
</fo:block>
</fo:float>ere, we have a drop cap that should be 3-lines high.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
Now is the time for all good men.
</fo:block>

ポイントは space-after="-8pt" で、これはfloatの中のBlockオブジェクトの空白の後ろを削除するものです。 そして、space-after.conditionality="retain" はspace-afterに指定して、referenceエリアのafter-edgeに有効なのです。
なお、space-before/after というのはreferenceエリアのbefore/after-edgeで無視されます。なぜならばspace-before/after-conditionalityのデフォルト値は"discard"（無視）だからです。