code: function rangeAtInnerBlockBoundary( range, block, checkEnd ) {
  		if ( !block )
  			return false;
  
  		var testRange = range.clone();
  		testRange.collapse( !checkEnd );
  		return testRange.checkBoundaryOfElement( block, checkEnd ? CKEDITOR.START : CKEDITOR.END );
  	}
docs: Checks whether range starts or ends at inner block boundary. See usage comments to learn more.