From LimeSurvey Manual
Add QCODE.question for question with sub-question (array, multiple choice ...) for Expression Script.
For example without this plugin : QCODE_SQ01.question show the text of subquestion SQ01 of question QCODE. But QCODE.question return an error because QCODE are not a related to a answer in survey. With this plugin QCODE return the question text of QCODE.