narrative around Medication.ingredient should be updated, or additional guidance added.  This comes from answering questions on the use of Medication.ingredient for compounded products.  I will work on the specific changes.

these are notes for further development

• Medication.ingredient can be used for both manufactured and compounded products.
• If the product is fully specified by Medication.code (e.g., RxNorm 570079 | acetaminophen 250 MG / aspirin 250 MG / caffeine 65 MG [Excedrin]), then Medication.ingredient is duplicative.  However, there may be situations where a particular component of the product needs to be called out.
• Even if a product is not “fully specified” (a patient says they take Maalox Max), most OTC products will be known by a systems’ medication database and Medication.ingredient will again be duplicative.
• For compounded products, Medication.ingredient (and MedicationKnowledge.ingredient) is the mechanism to define the components (active and other) in the product. 

• Medication.ingredient.strength is the strength of that ingredient in the prepared product.  The ingredient.item[x] may be simple (e.g., acetaminophen) or fully specified (e.g., acetaminophen 500 mg tablet), but ingredient.strength is what is seen in the final product.
• Medication.ingredient.strength.denominator can cause some confusion.  For example, the concentration of a pediatric acetaminophen suspension can be ‘32 mg / 1 ml’ or ‘160 mg / 5 ml’.  Why and which to use?  Both strengths are the same (32 x 5 = 160).   In clinical systems (drug databases) strengths are usually to unit volumes (32 mg / 1 ml).  While on a consumer product it’s preferred to say how much per “typical” dose: 160 mg / 5 ml, with 5 ml (1 tsp) being the typical dose.
• An issue that came up with the ‘other’ compound question (the question I kept mixing up with yours):  I’m not sure what to do with strength when the ingredient.item[x] is a combination product.  The compound question had “aluminum & magnesium hydroxide with simethicone 400-400-40 mg/5ml” as an ingredient (Maalox Max).  ingredient.strength doesn’t support multiple components.  You can decompose the ingredient into it’s parts.  In my answer, I took advantage of the Maalox Max being the base ingredient and used the nullValue of “qs” – this means “quantity sufficient” to bring the mixture to a specified volume (qs (Latin quantum sufficit) is a pharmacy abbreviation, like bid and hs).

• Medication.ingredient does not specify the total amount of the product, whether that is a number of tabs/caps, a total volume, or a total weight.  As such, one may not always be able to specify a “strength” of a BASE ingredient.  (this comes up in example 0319)