CCS Concepts: •  Software and its engineering  $\rightarrow$  Software maintenance tools .

ACM Reference Format:

1 INTRODUCTION

2 BACKGROUND

3 METHODOLOGY

4 RQ1: WHAT ARE THE RESEARCH TRENDS IN THE SURVEYED STUDIES?

5 RQ2: WHAT EFFORTS HAVE BEEN SPENT IN MCR STUDIES?

6 RQ3: WHAT IS THE RESEARCH STATUS OF THE SURVEYED MCR IMPROVEMENT TECHNIQUES?

7 RQ4: WHAT INSIGHTS HAVE BEEN GAINED FROM THE SURVEYED MCR UNDERSTANDING STUDIES?

8 RQ5: WHAT ARE THE CHALLENGES AND OPPORTUNITIES FOR MCR?

9 DISCUSSION

10 CONCLUSION