[xsl-fo] : Does FO support reusable style definition, similar to CSS?

Hi,

 

Newbie question, please:

Does FO support 'reusable formatting' definitions, similar to CSS "Class" ?
For example, suppose I have a document with 2 types of text:
- Heading, using font size 20pt
- Content, using font size 13pt

So , a naiive approach produces this page:
<fo:block font-size="20pt"> Some Heading  </fo:block>
<fo:block font-size="13pt"> Some content...  </fo:block>
<fo:block font-size="20pt"> More Heading  </fo:block>
<fo:block font-size="13pt"> More content...  </fo:block>


But this is difficult to maintain (e.g if I change my mind and want all headings to be 25pt).

Is there a better way ? Does FO support something like the 'Class' notion of CSS , so that you declare that 'MyHeading' means 'font size of 20', and from now on use it, something like:

 <fo:block class='MyHeading'>