code: function getContentFormTransformationGroup( form, preferredForm ) {
  		var element, left;
  
  		if ( typeof form == 'string' )
  			element = form;
  		else if ( form instanceof CKEDITOR.style )
  			left = form;
  		else {
  			element = form[ 0 ];
  			left = form[ 1 ];
  		}
  
  		return [ {
  			element: element,
  			left: left,
  			right: function( el, tools ) {
  				tools.transform( el, preferredForm );
  			}
  		} ];
  	}
docs: Return transformation group for content form. One content form makes one transformation rule in one group.