A large enterprise billing system handles standard contracts with millions of customers for consumer-market service packages. However, there is also a significant group of business and institutional clients purchasing services in large volumes — often outside of standard bundles. Due to the specific nature of these clients, negotiations are typically multi-stage and result in a custom contract, the structure and content of which differ substantially from standard templates — and may be subject to modification during the negotiation process. Each contract also refers to address-related data and service availability, both of which are maintained in the billing system. Moreover, once finalized, the contract information must be made available within the billing system as it directly impacts standard sales in the areas covered by the custom agreement.