What is the significance of the substitution made by s.13(ii), ibid., for "sale or purchase of goods takes place"?
The significance of the substitution made by s.13(ii), ibid., for "sale or purchase of goods takes place" is that it has updated and changed the previous language or phrasing used in the context to better reflect the current rules, laws, or provisions related to taxation on electricity and water storage, generation, consumption, distribution, or sale by authorities established by existing laws or laws made by Parliament for regulating or developing inter-State rivers or river-valleys. The substitution likely aims to clarify or modernize the language used in the original context to make it more understandable or applicable to current situations.