Structural Coverage Analysis Objectives

Software coverage analysis is used to determine which requirements were not tested.
This is supported by the structural coverage analysis objectives required by DO-178B that are intended to determine what software structures (e.g. statements or decisions) were not exercised as a result of these verification activities.
This, in turn, reveals requirements that may have been in error, tests that were lacking adequate coverage for these structures, or dead code.

SC, DC, MC/DC
DO-178B defines Statement Coverage, Decision Coverage and Modified Condition/Decision Coverage as follows:

Modified Condition/Decision Coverage (MC/DC) -
Every point of entry and exit in the program has been invoked at least once, every condition in a decision in the program has taken all possible outcomes at least once, every decision in the program has taken on all possible outcomes at least once, and each condition in a decision has been shown to independently affect that decision’s outcome.

Decision Coverage (DC) -
Every point of entry and exit in the program has been invoked at least once and every decision in the program has taken on all possible outcomes at least once.

Statement Coverage (SC) -
Every statement in the program has been invoked at least once.