code: private final String renderTagId(InternalStringBuilder buffer)
          throws JspException {
          assert(_name != null);
  
          // @todo: this is busted.  It should be writing out inline.
          String realName = rewriteName(_name);
          String idScript = mapLegacyTagId(_name, realName);
  
          // some tags will output the id attribute themselves so they don't write this out
          renderAttribute(buffer, "id", realName);
          return idScript;
      }
docs: This method will handle creating the tagId attribute.  The tagId attribute indentifies the
  tag in the generated HTML.  There is a lookup table created in JavaScript mapping the <coe>tagId</code>
  to the actual name.  The tagId is also run through the naming service so it can be scoped.  Some tags will
  write that <code>tagid</code> out as the <code>id</code> attribute of the HTML tag being generated.
  @param buffer
  @return String