Set line height using the line-height.
Source
<
fo:root xmlns:fo="
http://www.w3.org/1999/XSL/Format" >
<
fo:layout-master-set>
<
fo:simple-page-master master-name="simple">
<
fo:region-body/>
</
fo:simple-page-master>
</
fo:layout-master-set>
<
fo:page-sequence master-reference="simple">
<
fo:flow flow-name="xsl-region-body">
<
fo:block line-height="30pt">This is a paragraph with 30pt line height.
aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa
aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa
aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa
aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa
aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa
aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa
aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa
aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa
aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa
aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa
aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa aaa
</
fo:block>
</
fo:flow>
</
fo:page-sequence>
</
fo:root>