Yeah I saw those AUTHOR.XSL... etc too, don't really know what they're used for but they certainly don't affect that.

The line numbers I gave were valid for the Beta 2 Technical Refresh, looks like the file changed for the final version. It's line 2047 and 2058 now in the ISO690Nmerical.xslt file.

For reference, this the original version:

<xsl:template name="templ_prop_OpenBracket" >
  <xsl:param name="LCID" />
  <xsl:variable name="_LCID">
    <xsl:call-template name="localLCID">
      <xsl:with-param name="LCID" select="$LCID"/>
    </xsl:call-template>
  </xsl:variable>
  <xsl:value-of select="/*/b:Locals/b:Local[@LCID=$_LCID]/b:General/b:OpenBracket"/>
</xsl:template>

<xsl:template name="templ_prop_CloseBracket" >
  <xsl:param name="LCID" />
  <xsl:variable name="_LCID">
    <xsl:call-template name="localLCID">
      <xsl:with-param name="LCID" select="$LCID"/>
    </xsl:call-template>
  </xsl:variable>
  <xsl:value-of select="/*/b:Locals/b:Local[@LCID=$_LCID]/b:General/b:CloseBracket"/>
</xsl:template>


And after modification:
<xsl:template name="templ_prop_OpenBracket" >
  <xsl:param name="LCID" />
  <xsl:variable name="_LCID">
    <xsl:call-template name="localLCID">
      <xsl:with-param name="LCID" select="$LCID"/>
    </xsl:call-template>
  </xsl:variable>
  <!--<xsl:value-of select="/*/b:Locals/b:Local[@LCID=$_LCID]/b:General/b:OpenBracket"/>-->
  <xsl:text>[</xsl:text>
</xsl:template>

<xsl:template name="templ_prop_CloseBracket" >
  <xsl:param name="LCID" />
  <xsl:variable name="_LCID">
    <xsl:call-template name="localLCID">
      <xsl:with-param name="LCID" select="$LCID"/>
    </xsl:call-template>
  </xsl:variable>
  <!--<xsl:value-of select="/*/b:Locals/b:Local[@LCID=$_LCID]/b:General/b:CloseBracket"/>-->
  <xsl:text>]</xsl:text>
</xsl:template>


That should take care of it for the ISO690 Numerical style. If you use a different style you will need to find the equivalent sections in the other xslt files and modify those too.