What is the difference between a clinical terminology, a classification and a code system?

1). What is the difference between a clinical terminology, a classification and a code system? 2). How are these three groups related? 3). Give at least one example of the differences between the three and one example of how they are interrelated.

Explain the history of how that exclusion made it into the tax code and cite the history

About the exclusions from gross income. Please do the following 1. Pick an Exclusion 2. Explain what that exclusion means 3. Explain the history of how that exclusion made it into the tax code and cite the history 4. Explain the best and worst argument for this exclusion existing.