Tab stop positions

15.5.11 Tab Stops
says "The style:position attribute specifies the position of a tab stop."

But it doesn't specify the reference point for this position.
In particular I was given a .odt document with 

    <style:style style:name="Contents_20_2" style:display-name="Contents 2" style:family="paragraph" style:parent-style-name="Standard">
      <style:paragraph-properties fo:margin-left="0.423cm" fo:margin-right="0cm" fo:text-indent="0.002cm"/>
    </style:style>
    <style:style style:name="Contents_20_3" style:display-name="Contents 3" style:family="paragraph" style:parent-style-name="Standard">
      <style:paragraph-properties fo:margin-left="0.847cm" fo:margin-right="0cm" fo:text-indent="0.002cm"/>
    </style:style>
and
    <style:style style:name="P2" style:family="paragraph" style:parent-style-name="Contents_20_2">
      <style:paragraph-properties>
        <style:tab-stops>
          <style:tab-stop style:position="15.773cm" style:type="right" style:leader-style="dotted" style:leader-text="."/>
        </style:tab-stops>
      </style:paragraph-properties>
    </style:style>
    <style:style style:name="P4" style:family="paragraph" style:parent-style-name="Contents_20_3">
      <style:paragraph-properties>
        <style:tab-stops>
          <style:tab-stop style:position="15.349cm" style:type="right" style:leader-style="dotted" style:leader-text="."/>
        </style:tab-stops>
      </style:paragraph-properties>
    </style:style>
In OpenOffice.org, the position of the tab stop is actually aligned, between paragraphs of style P2 and P4.
The 0.4 cm difference in the tab-stop position is apparently compensated by the 0.4 cm margin-left.

Is it correct to say that the tab stop position starts after the left margin of the paragraph?
I think this should be clarified in the specification. I'll adjust the KOffice implementation accordingly.

-- 
David Faure, , sponsored by Trolltech to work on KDE,
Konqueror (http://www.konqueror.org), and KOffice (http://www.koffice.org).