code: function OpenXML_Rels_ReplaceTarget($RelsPath, $OldTarget, $NewTarget) {
  	
  		$idx = $this->FileGetIdx($RelsPath);
  		if ($idx===false) $this->RaiseError("Cannot edit target in '$RelsPath' because the file is not found.");
  		$txt = $this->TbsStoreGet($idx, 'Replace target in rels file');
  		
  		$att = 'Target="'.$OldTarget.'"';
  		$loc = clsTbsXmlLoc::FindStartTagHavingAtt($txt, $att, 0);
  		if ($loc) {
  			if ($NewTarget === false) {
  				$loc->Delete();
  			} else {
  				$loc->ReplaceAtt('Target',$NewTarget);
  			}
  			$this->TbsStorePut($idx, $txt);
  			return true;
  		} else {
  			return false;
  		}
  	
  	}
docs: Replace or delete a target in a Rels file.
  The current function actually edit the Rels file.
  Take car that there is another technic for listing and adding targets wish is working with a persistent object which is commit at the end of the merge..
  @param {string} $RelsPath  The path of the Rels file.
  @param {string} $OldTarget The target value to find.
  @param {string|boolean} $NewTarget The new target value, or false to delete the relation ship element.
  @return {boolean} True if the change is applied.