With this metric, Squish Coco counts which functions were called and how often. “Functions” includes also the member functions (or methods) in object-oriented programming languages like C++.
While this metric does not provide many details it can nevertheless be useful for an initial assessment of a project's test coverage status.
Relevance for Safety Standards
IEC 61508 highly recommends 100% structural test coverage of entry points (i.e. functions) for SIL 1, 2, 3 and 4.