the required code coverage includes modified condition/decision coverage (MC/DC). Here are several good resources explaining various aspects of this type of code coverage:
NASA – A Practical Tutorial on Modified Condition/Decision Coverage
FAA/CAST – What is a “Decision” in Application of Modified Condition/Decision
Coverage (MC/DC) and Decision Coverage (DC)?
FAA – An Investigation of Three Forms of the Modified Condition Decision Coverage (MCDC) Criterion