code: @Override
  	protected boolean isContentType(String schemaId, String schemaVersion, String systemId, String publicId) {
  		if (this.schema == null) {
  			return false;
  		}
  		if (this.regEx != null) {
  			final Matcher matcher = this.regEx.matcher(schemaId);
  			return matcher != null && matcher.find();
  		}
  		return this.schema.equalsIgnoreCase(schemaId);
  	}
docs: Replies if the specified stream contains data
  that corresponds to this magic number.
  
  @param schemaId is the ID of the XSL schema associated to this magic number.
  @param schemaVersion is the ID of the XSL schema associated to this magic number.
  @param systemId is the DTD system ID associated to this magic number.
  @param publicId is the DTD system ID associated to this magic number.
  @return <code>true</code> if this magic number is corresponding to the given
  XML document, otherwise <code>false</code>