id-attribute in bar-element removed even with `--remove-unreferenced-ids no`

[JoKalliauer]

Input

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE svg [
<!ATTLIST bar id ID #REQUIRED>
]>
<svg viewBox="0,0,480,360" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
 <defs>
  <text id="a">Hello</text>
 </defs>
 <!--======================================================================-->
 <!--=  SVG 1.1 2nd Edition Test Case                                     =-->
 <!--======================================================================-->
 <!--=  Copyright 2009 World Wide Web Consortium, (Massachusetts          =-->
 <!--=  Institute of Technology, European Research Consortium for         =-->
 <!--=  Informatics and Mathematics (ERCIM), Keio University).            =-->
 <!--=  https://www.w3.org/Consortium/Legal/2008/04-testsuite-license     =-->
 <!--=  See http://www.w3.org/Consortium/Legal/.                          =-->
 <!--======================================================================-->
 <d:SVGTestCase xmlns:d="http://www.w3.org/2000/svg" xmlnsd="http://www.w3.org/2000/02/svg/testsuite/description/" template-version="1.4" reviewer="ED" author="CL" status="accepted" testname="$RCSfile: text-tref-02-b.svg,v $">
  <d:passCriteria>
   <p>The test is passed if the phrase "Hello World" is displayed, in green.</p>
  </d:passCriteria>
 </d:SVGTestCase>
 <g font-family="SVGFreeSansASCII,sans-serif">
  <text fill="#008000" font-size="36" x="75" y="200"><tref xlink:href="#a"/> <tref xlink:href="#b"/></text>
  <!-- and another way to make a separate document fragment -->
  <foo xmlns="http://www.inkscape.org/namespaces/inkscape">
   <bar id="b">World</bar>
  </foo>
 </g>
</svg>

librsvg-rendering:

Output

<?xml version="1.0" encoding="UTF-8"?>
<svg viewBox="0,0,480,360" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
 <defs>
  <text id="a">Hello</text>
 </defs>
 <!--======================================================================-->
 <!--=  SVG 1.1 2nd Edition Test Case                                     =-->
 <!--======================================================================-->
 <!--=  Copyright 2009 World Wide Web Consortium, (Massachusetts          =-->
 <!--=  Institute of Technology, European Research Consortium for         =-->
 <!--=  Informatics and Mathematics (ERCIM), Keio University).            =-->
 <!--=  https://www.w3.org/Consortium/Legal/2008/04-testsuite-license     =-->
 <!--=  See http://www.w3.org/Consortium/Legal/.                          =-->
 <!--======================================================================-->
 <d:SVGTestCase xmlns:d="http://www.w3.org/2000/svg" xmlnsd="http://www.w3.org/2000/02/svg/testsuite/description/" template-version="1.4" reviewer="ED" author="CL" status="accepted" testname="$RCSfile: text-tref-02-b.svg,v $">
  <d:passCriteria>
   <p>The test is passed if the phrase "Hello World" is displayed, in green.</p>
  </d:passCriteria>
 </d:SVGTestCase>
 <g font-family="SVGFreeSansASCII,sans-serif">
  <text fill="#008000" font-size="36" x="75" y="200"><tref xlink:href="#a"/> <tref/></text>
  <!-- and another way to make a separate document fragment -->
  <foo>
   <bar>World</bar>
  </foo>
 </g>
</svg>

librsvg-rendering:

Copyright:

source https://commons.wikimedia.org/wiki/File:W3C_SVG_11_TestSuite_text-tref-02-b.svg

license https://www.w3.org/Consortium/Legal/2008/04-testsuite-license

author w3c SVG Working Group