- Test Report for Threshold Substances  a) “A” Sample Test Report   For Threshold Substances , the Laboratory  Test Report for the “A” Sample  shall establish that the identified Prohibited Substance (s) or its  Metabolite (s) or Marker (s) is present at a concentration and/or ratio and/or score of measured analytical values greater than the Decision Limit , and/or that the Prohibited Substance (s) or its  Metabolite (s) or Marker (s) is of exogenous origin.