text-align vs text-align-last

Is "text-align-last" has higher priority over "text-align" or not?
 
I could not find definitive ansver in the spec an tried to test it
empirically. Thus I create the following file and run all known
formatters over it:
 
<?xml version="1.0" encoding="UTF-8"?>
<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
 <fo:layout-master-set>
  <fo:simple-page-master master-name="only">
   <fo:region-body/>
  </fo:simple-page-master>
 </fo:layout-master-set>
 <fo:page-sequence master-reference="only">
  <fo:flow flow-name="xsl-region-body">
   <fo:block>
    <fo:block border="1px" margin="10px" text-align="left"
text-align-last="right">text-align="left"
text-align-last="right"</fo:block>
   </fo:block>
  </fo:flow>
 </fo:page-sequence>
</fo:root>
 
FOP and Ibex aligned text to the left side of the page
XEP and XSLFormatter aligned text to the right side
 
 
The question: which alignation should be used for the 1-line blocks if
"text-align" is not the same to "text-align-last" and why?