Answer:
A buying centre, also named a decision-making unit , gathers along "all those representatives of an company who engage in the purchasing process for a specific item or service"
The numerous positions are:
initiator: the initiator(s) attempts to buy a product or service, or acknowledges the issue, beginning the policy taking phase with this act.
Decider: Usually, policy managers don't have or require a specific mandate but have ample power inside the purchasing department to determine whether to acquire a service / brand.
Retailer: the retailer (also known as: procurement supervisor) chooses the vendors and handles the procurement in such a manner that the requisite goods are bought.
Influencer: The influencer refers to the design and selection of material or services requirements.
User: The user(s) are also the people who currently use the products or services.
Gatekeeper: the gatekeeper(s) manages the dissemination of information inside and outside the organisation, and the centre / team purchasing.