There are huge amounts of structural coverage criteria (see e.g. ISTQB-Standard or ISO26262-Standard), ranging from control-flow to data-flow coverage, applied to source code or to specifications.
So which coverage criteria are NOT structural?
Details: I can think of some non-structural coverage criteria, but have no idea whether there are more, and do not have a citable reference that covers non-structural coverage criteria.
Exemplary non-structural coverage criteria:
- Coverage of requirements
- Coverage of input values
- Coverage of GUI elements