Compounded Preparation - HC 1%, Salicylic Acid 5% in Glaxal Base - includes a reference to a substance in the ingredient element

{
  "resourceType" : "Medication",
  "id" : "med0319",
  "doseForm" : {
    "coding" : [{
      "system" : "http://snomed.info/sct",
      "code" : "385101003",
      "display" : "Ointment"
    }],
    "text" : "Ointment"
  },
  "ingredient" : [{
    "item" : {
      "concept" : {
        "coding" : [{
          "system" : "http://snomed.info/sct",
          "code" : "387253001",
          "display" : "Salicylic Acid (substance)"
        }]
      }
    },
    "strengthRatio" : {
      "numerator" : {
        "value" : 5,
        "system" : "http://unitsofmeasure.org",
        "code" : "g"
      },
      "denominator" : {
        "value" : 100,
        "system" : "http://unitsofmeasure.org",
        "code" : "g"
      }
    }
  },
  {
    "item" : {
      "concept" : {
        "coding" : [{
          "system" : "http://snomed.info/sct",
          "code" : "396458002",
          "display" : "Hydrocortisone (substance)"
        }]
      }
    },
    "strengthRatio" : {
      "numerator" : {
        "value" : 1,
        "system" : "http://unitsofmeasure.org",
        "code" : "g"
      },
      "denominator" : {
        "value" : 100,
        "system" : "http://unitsofmeasure.org",
        "code" : "g"
      }
    }
  },
  {
    "item" : {
      "concept" : {
        "coding" : [{
          "system" : "http://snomed.info/sct",
          "code" : "126066007",
          "display" : "White petroleum (substance)"
        }]
      }
    },
    "strengthRatio" : {
      "numerator" : {
        "value" : 94,
        "system" : "http://unitsofmeasure.org",
        "code" : "g"
      },
      "denominator" : {
        "value" : 100,
        "system" : "http://unitsofmeasure.org",
        "code" : "g"
      }
    }
  }]
}