I quote from the (version 2.0) documentation, class

suite

:

void add(const std::string& id, const testcase& t)

I understand that a test class has a name and that a test case has a name. Both are shown in test failure output.
But where is the name (o.k., “id”) used which is given to the dynamic association of a test suite with a test case, as it springs into logical existence by calling suite.add?