Before revision: If applicant can demonstrate that these levels of Model-Based requirements can accomplish the objectives for High-Level and Low-Level Requirements, then Development and Verification), supplement to DO-178C has clarified these aspects stating that high level requirements are requirements located prior to the model from which the model has been developed, the low level requirements being those located in the model itself.
After revision: Finally, the standard DO-331 ( Model-Based Development and Verification), supplement to DO-178C has clarified these aspects stating that high level requirements are requirements located prior to the model from which the model has been developed, the low level requirements being those located in the model itself.