Domestic Hot Water definition

Could someone give me the definition of domestic hot water systems? Would a water heater installed for a shower or a kitchen sink be considered a domestic hot water system? I recently received a review stating that "the documentation within PIf4: Schedule and Overview Documents indicates that the project scope of work includes domestic hot water systems", and asks for a confirmation that the domestic hot water system serving the tenant space has been included in the commissioning requirements. However, we are unclear as to what is being considered as domestic hot water systems by reviewers. In our opinion, there are no hot water systems in this project, since the building does not provide hot water to the project space. Could they be considering a domestic hot water system the water heater we intalled for the kitchen sink? Thanks!