A Tool-Based Perspective on Software Code Maintainability Metrics: A Systematic Literature Review

Table 2

Search strings for the selected digital libraries.

Library	Before refinement	After refinement
ACM Digital Library	+(“software” “code”)+(metrics)+(maintainability)	+(“software” “code”)+(metrics)+(maintainability)-(defect)-(fault)-(co-change)-(policy-driven)
IEEE Xplore	(((code OR software) AND metrics) AND maintainability)	((((((((code OR software) AND metrics) AND maintainability) NOT defect) NOT fault) NOT co-change) NOT policy-driven) NOT design)
Scopus	(code OR software) AND metrics AND maintainability	code OR software AND metrics AND maintainability AND NOT fault AND NOT defect AND NOT co-change AND NOT policy-driven AND NOT design
Web of Science	(code OR software) AND metrics AND maintainability	code OR software AND metrics AND maintainability NOT fault NOT defect NOT co-change NOT policy-driven NOT design